Some Skeptical Reviews
A test of the effect of reverse speech on
The Journal of Psychology; 5/1/2003; Voss, Carla W.
J. R. Vokey and J. D. Read (1985) indicated
that listeners cannot consciously recognize backward
messages but that some information can be obtained from
reversed speech. If reverse speech has a powerful influence
on language processing, as D. J. Oates (1991) has claimed,
then one should be able to measure a reliable priming effect
from reversed messages. Sixty undergraduate students
listened to short messages presented either backward or
forward. Immediately after listening to each message, they
responded in a lexical decision task to a visually presented
word that had either been present or had not been present in
the preceding message. No priming effect was found for
backward messages, although there was significant priming
for forward messages. The results are not consistent with an
effect of reverse speech on word processing.
Key words: repetition priming, reverse speech
IN AN ARTICLE IN THE SKEPTICAL INQUIRER,
Byrne and Normand (2000) critiqued claims made about the
effects of reversed speech. Oates (1991) claimed that
backward messages are encoded in normal speech and that this
constitutes a second, covert mode of communication in
addition to the overt mode of forward speech. This is a
recent version of long-standing claims made in the popular
media about the effects of backmasking (Vokey & Read, 1985).
Oates, however, did not confine his claims to negative
messages purportedly heard when popular musical recordings
are played backward but articulated a startling theory
suggesting that reverse speech is a normal part of human
communication. Oates claimed that these backward messages in
speech are not rarities but are normally encoded in everyday
speech. According to Oates, backward messages can reveal
unconscious memories and motives, and this information is
communicated unconsciously to listeners.
Byrne and Normand (2000) pointed out that
there is potential for harm in some of Oates's claims. For
example, Gates (1991) suggested that expert witnesses
trained in interpreting reversed messages could testify as
to the unconscious motives of a defendant. If Oates's theory
is not correct, this could potentially lead juries to wrong
verdicts. Byrne and Normand also questioned Oates's stated
goal of training individuals to open therapeutic practices.
Byrne and Normand argued that psychotherapy based on Oates's
theory would be unethical because the theory is so
It might be argued that Oates's (1991) claims
should simply be dismissed, given that they are potentially
dangerous and that the claims appear to be implausible.
However, we concur with Byrne and Normand (2000) that claims
such as these can and should be tested empirically.
Furthermore, the research literature does
include some evidence suggesting that information could be
obtained from reverse speech. A.L, a backward talker
described by Cowan, Leavitt, Massaro, and Kent (1982), was
able not only to reverse speech quickly but also to identify
correctly words that were presented backwards. This case
indicates that it is not beyond the capability of the human
brain to both use and recognize backward speech.
The question of whether backward messages can
be consciously identified by typical individuals has been
addressed by Vokey and Read (1985), who reported a variety
of results indicating that messages people hear in reversed
recordings are most likely the result of constructive
perception rather than of messages actually encoded in the
recordings. For example, Vokey and Read reported that
college students were unable to identify consciously a
reversed message until after they were told what the message
was. Also, students could not accurately determine whether
reversed messages were questions or statements.
At least some information from backward
messages is processed. Vokey and Read (1985) found that
college students could easily tell whether the speaker of a
backward message was a man or a woman and could tell whether
two backward messages were spoken by the same speaker or
different speakers. They could also discriminate among
languages (English, French, German) at a higher than chance
rate. Furthermore, students were slightly but significantly
above chance in telling whether a word read to them was or
was not present in a backward message they had just heard
(55.8% accuracy). However, students could not reliably
discriminate meaningful from meaningless sentences or sort
sentences into semantic categories.
The claim made by Oates (1991), however, is
not that reversed speech is consciously recognized but that
one processes it without being aware that one is doing so.
Although Gates made broad claims about intentions and
memories being encoded backwards in individuals' speech, we
focused our investigation not on whether backward messages
actually exist in normal speech but on the question of
whether these would have an effect on language processing if
they did exist.
There is considerable evidence for
unconscious processing of normally presented words. As
Jacoby and Kelley (1992) stated, "For experimental
psychologists, the investigation of unconscious influences
has gained new respectability from findings of dissociations
between performance on direct and indirect tests of memory
and perception" (p. 175). The term unconscious here refers
to processing without awareness. Although individuals with
amnesia perform poorly on tests of conscious recall, prior
exposure to words benefits them as much as it does ordinary
individuals on indirect tests, such as reading fragmented
versions of previously presented words (Jacoby & Kelley).
This suggests that individuals with amnesia are able to
process words without being aware that they are doing so.
It is possible that reversed messages could
have an effect on memory even if individuals do not
consciously recognize the words. There have been several
such tests of effects of reversed messages. Vokey and Read
(1985) reported that spelling of homophones was not affected
by the meaning of a homophone in a previously presented
backward message. Swart and Morgan (1992) presented messages
in backward recordings of music and found that the backward
messages (e.g., "Clean up your room") did not affect
Liken-scale attitude ratings for statements such as "Keeping
my bedroom clean and neat is important," even when the
message was presented six times.
Begg, Needham, and Bookbinder (1993)
investigated whether people would be more likely to view a
statement as truthful if it was previously presented
backward. Although college students could reliably
distinguish backward messages they had heard from those they
had not heard, their truth ratings of the messages they had
heard were not different from messages they had not heard.
However, students who heard the same messages played forward
did rate the messages they heard as more truthful than
messages they had not heard. Thus, forward messages affected
truth ratings, but backward messages did not.
It might be argued that these researchers
used dependent variables that were not sufficiently
sensitive to find an effect of the reversed messages.
Measures such as Likert-scale ratings provide a discrete set
of possible responses. If backward speech does have an
effect, then it may be more likely to appear in a continuous
measure such as the time to choose a response rather than'
in a measure of which response is chosen. Therefore, in the
present study we measured repetition priming to words in a
lexical decision task. We used examples of reversed messages
provided by Qates (1991) so that it cannot be claimed that
the stimuli were artificial or unrepresentative of the types
of messages that should affect listeners. If reversed speech
does affect word processing, there should be a significant
amount of priming from reversed messages in the lexical
decision task. As a control, we also measured priming to
messages presented in their normal forward form. If we
observe priming to forward messages, it would sugges t that
a failure to find an effect of backward messages is not the
result of a limitation of the method.
Sixty students attending Central Missouri
State University volunteered to participate. They received
extra credit in psychology courses in exchange for their
Twenty messages that Oates (1991) has claimed
exist in reversed speech samples were obtained from the
Reverse Speech Enterprise's Web site (http://reversespeech.s3.amazonaws.com).
We selected messages that appeared to have some emotional
content but that did not include obscene language (see
Appendix A). Of the 20 remaining messages, 12 were used for
real word trials and 8 were used for pseudoword trials. Each
message was digitally recorded by a woman. Reversed versions
of each message were created using SoundEdit[TM] 16
software. The messages ranged in duration from 726 to 1,852
ms with a mean duration of 1,380 ms (SD = 285). For 12 of
the 20 messages, a content word from the message was
selected for use in the lexical decision task. For the
remaining 8 messages, a pseudoword was constructed by
replacing two letters in the content word for each message.
We recorded four additional messages and used them for
The number of real word trials was greater
than the number of pseudoword trials as a result of the
limited number of stimuli that met our criteria of being
emotional but that did not include obscene language. It was
necessary for the number of real word trials to be a
multiple of 4 so that we could create four stimulus lists to
counterbalance the items across forward and backward
conditions as well as across priming and control trials. To
satisfy this constraint, we used 12 of the 20 messages for
real word trials, leaving 8 messages for pseudoword trials.
Although participants encountered more words than nonwords,
the small total number of trials made it unlikely that
participants had time to develop a bias in responding across
The four stimulus lists are shown in Appendix
B. Each list contained 8 pseudoword trials and 12 trials
with real words. Six of the real word trials on each list
were priming trials in which the target word for the lexical
decision task was contained in the message (priming trials).
The other 6 real word trials were control trials in which
the target word in the lexical decision task was a word not
contained in the message (control trials). For three of the
priming trials and three of the control trials, the message
was presented in reversed form; for the other half of these
trials, the message was presented in forward form.
The same words were used as control trials
and priming trials for different participants. Words were
counterbalanced across stimulus lists so that each word
occurred on all four types of trials (i.e., forward and
backward priming and control trials). Each word occurred
once on each stimulus list. Thus, each participant
encountered each message and each word only once during the
course of the experiment. Forward messages were presented on
half of the pseudoword trials, and reversed messages were
presented on the other half.
After reading and signing an informed consent
form, the participants read instructions on a computer
screen and placed headphones on their heads before beginning
the experiment. Stimuli were presented and responses
recorded by using Reaction Time 3.0 software. Four practice
trials were followed by the 20 experimental trials. On each
trial, the message was presented over the headphones. Three
seconds after the beginning of the message, a word or
pseudoword was presented in lowercase letters in the center
of the screen. Because the messages varied in length, this
produced variability in the interval between the end of the
message and the appearance of the word or pseudoword.
The participants responded by pressing a key
marked YES if they believed the item was a real word or a
key marked NO if they believed it was not a real word. We
instructed the participants to respond as quickly as they
could while still being accurate. There was a 2-s interval
between trials during which the word READY appeared at the
top of the screen. Trials were presented in random order for
each participant, and 15 participants were tested for each
of the four stimuli lists. Each participant was debriefed
immediately after participating.
We computed priming for each participant by
subtracting mean reaction time on priming trials from mean
reaction time on control trials. Only times for correct
responses were included. Data were excluded for three
additional participants who had fewer than two out of three
correct trials for any of the four groups of real word
trials, yielding a total of 60 participants for all of the
results reported below. The mean number of errors out of 20
trials was 0.93 (SD = 1.10).
For forward messages, the mean priming was 97
ms (SD = 201); for backward messages, the mean priming was
10 ms (SD = 359). We conducted single-sample t tests to
determine whether the amount of priming was significant for
forward or backward messages. Forward message priming was
significantly different from zero, t(59) = 3.74, p < .001,
[r.sup.2] = .19, but backward message priming was not, t(59)
= 0.22, p> .05, [r.sup.2] = .00. Mean reaction times are
shown in Table 1.
The number of errors was not significantly
correlated with overall reaction times, r(58) = -.02, p>
.05. The total number of errors was not significantly
correlated with the amount of priming from backward
messages, r(58) = -.14, p> .05. However, the participants
who made more errors tended to show less priming from
forward messages, r(58) = -.36, p < .01.
There was no indication that backward
messages caused priming. The amount of backward priming was
not statistically significant and the effect size was zero.
It is unlikely that the lack of a backward message priming
effect was because of low power or to poor sensitivity of
the research method, as the same method, using the same
stimuli, produced a clear priming effect with forward
messages. It is also difficult to argue that the stimuli
used were not realistic or emotional enough to elicit a
priming effect if one existed, as we used messages that
Oates (1991), a proponent of reverse speech, claimed to find
in natural speech samples.
The variability of reaction times within
conditions was quite large. This is likely a result of the
fact that there were only three trials within each condition
for each participant. Despite these large standard
deviations, there was still a significant priming effect
from the forward messages.
It should be noted that a repetition priming
paradigm was used in the present study; the same word to
which participants responded in the lexical decision task
was contained in the backward or forward message. Another
approach could be to use a semantic priming paradigm in
which participants respond to a word that is semantically
related to the word in the message (e.g., wolf and dog). We
chose to use the repetition priming approach for several
reasons. First, we wanted to use a method that would provide
a high probability of detecting an effect of backward speech
if such an effect existed. Repetition priming tends to
produce large effects, and these effects have been found
even when participants claim that they have not recognized
the word (Stark & McClelland, 2000). This is important,
because Oates (1991) claimed that we process information
from reverse speech without being consciously aware that we
are doing so.
The method we actually used was cross-modal
repetition priming, because the message was presented in
auditory form and the stimuli in the lexical decision task
were presented visually. Cross-modal repetition priming
(with normally presented stimuli) has been shown by
Grainger, Van Kang, and Segui (2001). A second reason that
we did not use a semantic priming approach is that it would
have been difficult to find appropriate semantic primes that
were strongly associated with only one word on the limited
list of stimuli that we obtained from Oates's website. It is
typically assumed that the presentation of a spoken word
activates orthographic representations as well as semantic
codes (Grainger et al.); thus, any orthographic or semantic
processing of the backward messages should have resulted in
a priming effect in the lexical decision task. It is
therefore unlikely that a semantic priming study would
produce any effect of backward messages.
A.L., the individual described by Cowan et
al. (1982), was able to identify correctly 11 of 19
backward-spoken words, whereas controls in the Cowan et al.
study correctly identified no more than 4 words. Therefore,
it is at least possible that the human brain can recognize
backward speech. However, the case of A.L. is extraordinary,
as shown by the performance of the controls as well as by
the results of Vokey and Read (1985). Oates (1991) claimed
that backward speech processing is a normal part of human
communication; therefore, the ability to process it should
not be rare.
Swart and Morgan (1992) and Begg et al.
(1993) did not find any influence of backward messages on
attitude ratings or on truth judgments, respectively.
However, these researchers did not test for effects on word
processing in particular nor did they measure response
times. Our results provide converging evidence, using a
reaction time measure in a lexical decision task, that
backward messages do not affect the processing of words. It
is important to note that the method we used did not require
participants to be aware of recognizing words in the
backward messages. The claim that backward speech
unconsciously (i.e., without awareness) affects language
processing is therefore not consistent with our results.
Of course, it is not possible to prove that
the null hypothesis is correct. However, there are now
several studies, using different methods, that have not
shown any effect of backward speech. Furthermore, we
demonstrated the expected effect of forward messages, as did
Begg et al. (1993), suggesting that the failure to find an
effect of backward messages was not because of a lack of
power in the research design. Oates (1991) suggested that
the effects of backward speech are at least as powerful as
those of normal overt speech. Our results indicate that it
is very unlikely that reverse speech has an effect on
Messages and Target Words Used
Cuddle me. cuddle lie
Hear the lie. lie cuddle
Her name was mocked. mocked kill
I know who to kill. kill mocked
Sealed the lock. lock wolf
Wolf in white van. wolf lock
You lady mannequin. lady plant
This is a plant. plant lady
Man will space walk. space shot
He's shot bad. shot space
Evil lips are hammering it. evil grass
They pulled out the grass. grass evil
That's the jive I was
Make me some
Here I am, rubber duck.
Yes I'm not
The fuss will serve
1 List 2
Cuddle me. forward priming
Hear the lie. forward priming
Her name was mocked. forward priming
I know who to kill. backward priming
Sealed the lock. backward priming
Wolf in white van. backward priming
You lady mannequin. forward control
This is a plant. forward control
Man will space walk. forward control
He's shot bad. backward control
Evil lips are hammering backward control
They pulled out the backward control
That's the jive I was pseudo
Make me some money. pseudo
Here I am, rubber duck. pseudo
Yes I'm not brave. pseudo
Get our funds. pseudo
You were smashed. pseudo
I'm with love. pseudo
The fuss will serve us. pseudo
3 List 4
Cuddle me. forward control
Hear the lie. forward control
Her name was mocked. forward control
I know who to kill. backward control
Sealed the lock. backward control
Wolf in white van. backward control
You lady mannequin. forward priming
This is a plant. forward priming
Man will space walk. forward priming
He's shot bad. backward priming
Evil lips are hammering backward priming
They pulled out the backward priming
That's the jive I was pseudo
Make me some money. pseudo
Here I am, rubber duck. pseudo
Yes I'm not brave. pseudo
Ger our funds. pseudo
You were smashed. pseudo
I'm with love. pseudo
The fuss will serve us. pseudo
Mean Reaction Times (ms) on Lexical Decision
Message type M SD M
SD M SD
Forward 1,220 333 1,317
344 1,563 542
Backward 1,302 460 1,312
361 1,617 638
Original manuscript received August 31, 2001
Final revision accepted August 29, 2002
Begg, I. M., Needham, D. R., & Bookbinder, M.
(1993). Do backward messages unconsciously affect listeners?
No. Canadian Journal of Experimental Psychology, 47, 1-14.
Byrne, T., & Normand, M. (2000, March/April).
The demon-haunted sentence: A skeptical analysis of reverse
speech. Skeptical Inquirer, 46-49.
Cowan, N., Leavitt, L.A., Massaro, D. W., &
Kent, R. D. (1982). A fluent backward talker. Journal of
Speech and Hearing Research, 25, 48-53.
Grainger, J., Van Kang, M. N., & Segui, J.
(2001). Cross-modal repetition priming of heterographic
homophones. Memory & Cognition, 29, 53-61.
Jacoby, L. L., & Kelley, C. M. (1992). A
process-dissociation framework for investigating unconscious
influences: Freudian slips, projective tests, subliminal
perception, and signal detection theory. Current Directions
in Psychological Science, 1, 174-179.
Oates, D. J. (1991). Reverse speech: Hidden
messages in human communication. Indianapolis, IN: Knowledge
Stark, C. E. L., & McClelland, J. L. (2000).
Repetition priming of words, pseudowords, and nonwords.
Journal of Experimental Psychology: Learning, Memory and
Cognition, 26, 945-972.
Swart, L. C., & Morgan, C. L. (1992). Effects
of subliminal backward-recorded messages on attitudes.
Perceptual and Motor Skills, 75, 1107-1113.
Vokey, J. R., & Read, J. D. (1985).
Subliminal messages: Between the devil and the media.
American Psychologist, 40, 1231-1239.
We thank Joseph J. Ryan for pointing out the
Skeptical Inquirer article that led to this research. We
also thank the editors of The Journal of Psychology for many
Address correspondence to David S. Kreiner,
Department of Psychology, Lovinger 1111, Central Missouri
State University, Warrensburg, MO 64093-5089; email@example.com
COPYRIGHT 2003 Heldref Publications
This material is published under license from the
publisher through the Gale Group, Farmington Hills, Michigan.
All inquiries regarding rights should be directed to the Gale
HighBeam™ Research, LLC. © Copyright 2004. All
CA); 6/22/2000; ANDERSON, JOHN CHRIS
Test of the
Speech Hypothesis: Are Listeners Able to Detect the
Emotional Content at Backward Speech?
THE HEIGHT OF THE SCANDAL involving Monica Lewinsky if President
Clinton had said during his Grand Jury testimony, "Kiss the
lying ass," it would have caused quite an uproar. According to
David John Oates, Clinton said precisely that. Only he said it
backward while simultaneously responding to a question about his
testimony in a previous deposition. Furthermore, Clinton was not
aware he was saying "Kiss the lying ass" because it was placed
into his speech stream by his unconscious mind. How is
this possible? The mechanism is described by Oates in his book
Reverse Speech: Voices from the Unconscious (see
also his web page: www.reversespeech.com). 
Oates claims to have discovered that speech actually
contains two signals. The forward message is constructed by the
left hemisphere and is produced and perceived by the conscious
mind. As that is happening, a backward message is being
constructed by the right hemisphere representing thoughts and
issues in the unconscious mind. The backward message serves a
psychodynamic purpose for the speaker. Much as other defense
mechanisms can be used to deal with unpleasant information in
the unconscious, reverse speech allows a safe
outlet for information that would otherwise overwhelm the person
According to Oates, the implications of his discovery are truly
enormous. We agree that if true, they would be. Backward
messages, he says, reveal the truth about people's mental
states, their internal conflicts, and even the way they fit into
the cosmological structure of the universe. Reverse
speech has practical implications (serving as a lie detector
for job interviews and police departments) and therapeutic
applications (by revealing the true state of the unconscious, it
is possible for a therapist to know precisely what treatments
Many of the reversals that Oates finds are actually metaphors
that he claims come from the collective unconscious (as
described by Jung). It is the job of the reverse
speech analyst to interpret those metaphors and explain what
they mean. It takes years of practice to become a reverse
speech analyst. Part of the training involves how to hear
speech in the "gibberish" of the signal. Other training
teaches the analyst the metaphors used in reverse speach.
Without understanding the metaphors, the statements made in
reverse speech make little sense.
The purpose of the research reported here was to test some of
the claims made by Oates for the reverse speech
hypothesis. One might wonder why a hypothesis that makes such
fantastic claims is worthy of serious attention. The reasons are
clear. If the hypothesis is correct the implications are as
far-reaching as Oates and his followers claim. Businesses, the
police, and even the partners of unfaithful spouses will have a
new tool at their disposal for ferreting out the truth.
Furthermore, therapists will be able to gain new insight into
their patients' thought processes, making for more effective
treatment. On the other hand, if the hypothesis is wrong, a lot
of wasted time and effort can be saved. Clients can be spared
the trouble of undergoing an ineffective treatment. Innocent
people can avoid being accused, tried, and convicted, as they
were in the early 1990s when belief in facilitated communication
inspired fantasies of sexual abuse in facilitated conversations.
The reverse speech hypothesis makes two claims
that can be tested empirically: 1. Backward messages are being
embedded into forward speech by the unconscious. 2. These
messages can be perceived and understood by listeners. One could
argue that the second claim is not all that unreasonable.
Surprisingly, reversing speech does preserve a fair
amount of the available phonetic information. Begg, Needham, and
Bookbinder demonstrated that sentences played backward can be
recognized later.  Saberi and Perrott demonstrated that if
speech is cut into segments of up to 50 milliseconds (ms),
and each segment is then reversed, listeners report
perfect intelligibility.  There is also evidence to suggest
that some aspects of meaning are related to phonological
information. For example, the phonetic symbolism effect is that
words describing small things (e.g., "teeny") tend to use high,
front vowels, and words describing large things (e.g., "huge")
tend to use low, back vowels.  Perhaps the unconscious can
take ad vantage of these sorts of regularities to comprehend
is the claim that listeners can unconsciously perceive the
content of reverse speech that we test in the
experiments reported below. We begin by reviewing some relevant
literature on the nature of unconscious processing. Then, we
consider research into listeners' ability to detect backward
messages in rock albums. Finally, we employ a methodology that
has the best chance of allowing listeners to detect the meaning
of reverse speech.
THE UNCONSCIOUS SMART OR DUMB?
Loftus and Klinger asked the question "Is the unconscious smart
or dumb?"  They defined several possible criteria for what
makes an unconscious process smart: it is complex, it can deal
flexibly with a novel situation, or it always does what is best
for us. As in most psychodynamic theories, the reverse
speech hypothesis would not include an endorsement of the
third criterion. There are many ways in which the reverse
speech hypothesis' version of the unconscious could be
harmful; perhaps the simplest is that by using reverse
speech as an outlet, the unconscious is revealing secret
information that any listener can detect.
The reverse speech hypothesis does include the
claim that the unconscious is smart according to the first two
criteria. A process that can make minor tweaks to a forward
message and still produce a meaningful utterance every 10-15
seconds would have to be complex, as would a process that could
extract the information from the speech stream. The
unconscious of the reverse speech hypothesis would
also have to be able to deal with novel situations. For example,
Oates claims it is possible for two people to carry on a
backward, unconscious conversation while they are also having a
forward conversation. Carrying on a conversation is certainly an
activity that is unique to particular situations and would
require a flexible process. Is there evidence that the
unconscious is smart in this way?
Greenwald, in his "New Look 3," proposed that unconscious
cognition is possible. He described three levels of unconscious
processing that have been explored: physical features, single
words, and multiword strings. Based on experiments using
subliminal activation and selective attention to uncover effects
of unconscious processing on activation, memory, and retrieval,
Greenwald concluded that the unconscious analysis of physical
features has been established and that some effects of single
words have been obtained. However, "These studies have provided
no evidence that can confidently be interpreted as indicating (attentionless)
unconscious analysis at the level of multiword strings."  He
thus concluded that "Unconscious cognition has been found to be
severely limited in its analytic capability."
other words, the kind of smart unconscious proposed by the
reverse speech hypothesis is not supported by
research on unconscious processing. In fact, Greenwald issued a
challenge to find evidence that unconscious processes can
extract the meaning of even a two-word sentence. This is hardly
the level of sophistication required if the reverse
speech hypothesis were correct, and it would be a severe
condemnation of unconscious processing if the two word test
sum, research into the types of tasks that can be performed
unconsciously suggests that the processes proposed by the
reverse speech hypothesis are beyond the analytical
capabilities of the unconscious. However, one could make the
case that all that is really being postulated is an automatic
process akin to those that assist in comprehending forward
speech (like lexical retrieval). Evidence that the
unconscious isn't smart does not, by itself, rule out the
reverse speech hypothesis. Whether or not listeners
can comprehend the meaning of backward speech is an
CAN LISTENERS DETECT MEANING IN BACKWARD SPEECH?
Research has been conducted to investigate people's ability to
detect the meaning of backward speech in the context of
backward messages embedded in popular music. This research was
inspired in part by religious leaders' claims that satanic
messages are hidden in rock music, and by a court case in which
it was claimed that two young men committed suicide because the
message "do it" was hidden in a rock album.  The results of
this research can be summed up quite simply: listeners are
sensitive to the physical characteristics of backward messages,
but they cannot discern the meaning of those messages.
Vokey and Read showed that people can discriminate male from
female voices in backward speech (98% correct), can
detect a change from one speaker to another (78% correct), and
can determine the (forward) language of backward speech
(47% correct for sorting amongst three languages). However, with
these same backward speech stimuli, listeners could not
tell statements from questions, could not tell if two statements
had the same or different meaning, and could not tell if the
statements made sense. Listeners were also unable to sort
backward messages into the categories of nursery rhymes,
Christian, satanic, pornographic, or advertising. 
Begg, et a1 extended Vokey and Read's results by showing that
even if the backward messages are memorable, their meaning does
not "'leak' through." They played messages to participants
either forward or backward. All participants then attempted to
determine if backward statements were old or new. Participants
who had first heard the statements played backward were able to
tell old from new statements better than participants who had
only heard the statements played forward. So, participants were
able to extract information about the physical features of the
statements (as Vokey and Read found), and they had some memory
of what they had heard. 
After the recognition task, participants were asked to rate
forward versions of each statement as true or false. Begg, et a1
expected an illusory truth effect for participants who had
extracted the meaning of the statements when they were first
presented. Participants who had heard the forward statements did
show an effect; participants who had heard the statements played
backward did not. The researchers concluded that participants
can extract information about the physical features of backward
messages, but they cannot extract information about the meaning
of the messages. They left the question open of whether or not
listeners would be able to unconsciously perceive the emotional
content of backward speech. Is there any evidence for the
unconscious perception of emotional information?
EMOTIONS AND UNCONSCIOUS
Kunst-Wilson and Zajonc demonstrated that affective judgments
could be made on the basis of information that participants did
not consciously perceive. They prepared a number of distorted
octagons that had sides of varying lengths that gave each a
distinctive shape. The various kinds of octagons were presented
for i millisecond under constrained viewing conditions.
Participants were generally unaware of seeing anything more than
a flash of light, and could not reliably discriminate later
between octagons they had seen before and new, differently
proportioned octagons on a subsequent forced choice task,
supporting the claim that the initial perception was
unconscious. However, when participants were asked to choose
which of two shapes they liked better, they preferred shapes
they had actually seen before to shapes they had never seen at
above chance levels. 
number of studies have shown that in anxious individuals
threat-related information produces interference. [13, 14] This
may possibly be due to a pre-attentive process. [15, 16] This
type of effect is reasonable from an evolutionary perspective.
Since the function of anxiety is to alert an organism that some
sort of threat is present--even if that threat is presented in a
brief exposure, or attention is directed somewhere else when the
threat appears--anxiety is the ideal emotion to be perceived
outside of conscious awareness.
Ohman makes the case that anxiety detection is hard-wired and
can operate in an unconscious fashion.  He cites work by
LeDoux showing that in rats there is a direct neural connection
from auditory nuclei to a "significance evaluator" and "fear
effector system" in the amygdala.  This pathway bypasses the
route that analyzes a stimulus for meaning. Ohman proposes in
his model for the generation of anxiety that it can more
"plausibly be attributed to some gross and relatively simple
features of the stimuli than to a complete analysis of their
meaning." In other words, the generation of anxiety is exactly
the kind of dumb process that the unconscious should be capable
of carrying out.
Given that anxiety can arise due to information that is not
consciously perceived, it is possible that anxiety-producing
information presented in reverse speech may be
unconsciously perceived as well. This notion will be the basis
for the experiments reported below.
HYPOTHESES AND GENERAL PREDICTIONS
The same basic procedure was used for both of the experiments.
Emotionally arousing information was recorded. This information
was then played to participants either forward or backward, and
they rated their arousal. We pitted two hypotheses against one
another in the experiments. The prediction of the reverse
speech hypothesis is that listeners will detect the
emotional content of messages, even if they are played backward.
In other words, there will be a difference between arousing
information and neutral information; the direction in which the
material is presented will have no effect.
The altemative hypothesis is that the emotional content of
backward speech will not be perceived. If true, then
increased arousal will only be found for arousing materials
played forward. In other words, we are predicting an
interaction. When the material is played forward, arousal will
be high for arousing information, but not for neutral
information. When the material is played backward, arousal will
below for both kinds of information.
The question for the first experiment was this: Will listeners
be able to detect the emotional content of arousing words played
in reverse? For the first experiment the stimulus
materials were lists of words that were either arousing or
neutral. These lists of words were played either forward or
The arousing words were infected, polio, mutilated,
breathlessness painful, deformed, surgery, hospital, ambulance,
wound, blood, burial, burns, choking, heart attack, hurt, germs,
sickness, tumor, collapse, corrosive, accident, attack, drowned.
The neutral words were depicted, agency, cable, tenant, house,
stay, chart, woodpile, lamp, signature, reverse,
assembly, camera, terminology vehicle, luggage, napkins, wall,
sand, news, pencil, between, end, glass. Both lists of words
were adapted from Lundh and Ost.  One male experimenter
digitally recorded the word lists 16 times each to produce a
stimulus long enough to affect arousal. These lists were
transferred to cassette tapes. The neutral tape was 11 minutes
and 38 seconds long; the arousing tape was 11 minutes and 44
seconds long. Reversed versions were made by reversing
each list and transferring the reversed lists to cassette
Arousal was measured using the adjective checklist from Mackay
et al.  Participants rated 15 adjectives as to whether those
adjectives applied to them at that moment. The adjectives (in
the order they were presented) were drowsy, tired, vigorous,
activated, stimulated, alert, idle, energetic, passive, aroused,
active, somnolent, sleepy, lively, sluggish. Scores could range
from 0 to 15, with higher scores meaning more arousal.
The experimenters recruited 45 people to participate in the
experiment. Most of these participants were college students;
all participation was voluntary. The participants were run one
at a time. The experimenters told participants that they would
be listening to a list of words. The participants were warned
that they would rate some adjectives after the list. The
experimenters then played the list of words to the participant.
After the list, the participant was given the arousal checklist.
The data were analyzed using an independent samples Analysis of
Variance (ANOVA) comparing the list type (arousing, neutral) and
the direction (forward, backward). The prediction from the
reverse speech hypothesis was that the arousal and
neutral lists would differ in the amount of arousal produced,
but this difference was not significant [F(1,41) = 1.24, MSE =
14.01]. The mean amount of arousal for the arousing list was
5.70 and the mean amount of arousal for the neutral list was
predicted by the alternative hypothesis, there was a significant
interaction between the list type and the direction in which the
lists were played [F(1,41) = 4.65, MSE = 14.01]. For lists
played forward, the arousal score for the arousing list was
higher than the arousal score for the neutral list. For lists
played backward the arousal scores for the arousing and neutral
texts did not differ. These data are illustrated in FIGURE 1.
The results are clear. When arousing words are played forward,
they produce arousal. When arousing words are played backward,
they do not. In addition to fitting quite well with the
prediction from the alternative hypothesis, this result is
exactly what was predicted for the apprehension of emotional
content from backward speech by Begg et al.
One possible criticism of this study is that it does not reflect
the natural task facing listeners. For example, if a listener is
unconsciously evaluating the content of a politician's
speech, the stimulus is not a list of words, but rather a
connected discourse. Is it fair to claim that results from a
word list will generalize to real speech? The second
experiment was designed to answer this objection.
The stimuli for the second experiment were taken from the novel
The Hot Zone  The arousing text was 4 minutes and 44 seconds
long. It described a man dying from the Ebola virus on an
airplane. The passage was extremely unpleasant, and it was
chosen to produce a considerable amount of arousal in the
participants. The tone of the passage can be gleaned from the
The airsickness bag fills up to the brim with a substance known
as the vomito negro, or the black vomit. The black vomit is not
really black; it is a speckled liquid of two colors, black and
red, a stew of tarry granules mixed with fresh red arterial
blood. It is a hemorrhage, and it smells like a slaughterhouse.
The neutral passage was taken from a part of the book describing
a visit to a mountain rainforest. This passage was 4 minutes and
48 seconds long. A sample is:
traveled in two Land Rovers, Carrie driving one and Robin
driving the other... Carrie and Robin's two boys rode with
Carrie. We were also accompanied by three men who were members
of the MacDonalds' safari staff. Their names are Katana Chege,
Herman Andembe, and Morris Mulatya. They are professional safari
men, and they do most of the work around the campsite.
Although we have substituted more natural stimuli in the second
experiment, the two hypotheses make the same predictions as in
the first experiment. If the reverse speech
hypothesis is correct, we would expect more arousal for the
arousing text than the neutral text regardless of whether it is
played forward or backward. For the alternative hypothesis, we
would expect increased arousal only for the arousing text played
One male experimenter digitally recorded both excerpts. Forward
and backward versions of these were copied onto cassette tapes
for presentation to participants. A total of 83 students from
psychology courses participated in the experiment, for which
they received extra credit. For each session, participants were
told that they would listen to someone speaking and then rate
some adjectives. The appropriate tape was played, and the
adjective checklist was handed out immediately after it
The data were analyzed using an independent samples ANOVA
comparing the text type (arousing, neutral) and the direction
(forward, backward). Once again, the prediction from the
reverse speech hypothesis was that the arousal and
neutral texts would differ in the amount of arousal produced.
The means for arousing and neutral were 5.88 and 2.64,
respectively. This difference was significant [F(1,79) = 15.92,
MSE = 13.59]. However, the interpretation of this difference is
qualified by the interaction between the two variables, which
was significant [F(l,79) = 7.73, MSE = 13.59]. When the text was
played forward, the arousal score was lower for the neutral
paragraph than for the arousing paragraph. When the text was
played backward the arousal scores for the neutral and arousing
paragraphs did not differ. These data are illustrated in FIGURE
2. Even though there is an overall difference between arousing
and neutral texts, that difference results from when the texts
are played forward. As with a list of words, when a text is the
stimulus the reverse speech hypothesis cannot
account for the results.
The results of the two experiments are remarkably consistent
Highly arousing information only produces arousal if it is
played in the forward direction. When arousing information is
played backward, it is no longer arousing. Given the results of
previous research on listeners' ability to unconsciously
perceive the meaning of backward speech, our are not
surprising. However, these experiments do show that even for
arousal--something that is probably hard-wired into the
perceptual system and that can arise from stimuli that are not
themselves consciously perceived --information in backward
speech does not get through to a listener. This is true
even though reversing speech preserves most of the
phonetic information of forward speech.
IMPLICATIONS FOR THE REVERSE SPEECH HYPOTHESIS
How much damage do our results do to the reverse
speech hypothesis? At this point, the second claim (that
listeners can perceive the meaning of reverse speech)
has been proven false. The semantic content does not get
through, and neither does the emotional meaning. The first claim
(that speakers embed backward messages into speech) has
been left relatively intact. However, we have two reasons why we
think this part of the hypothesis may also be wrong.
First, a number of studies have shown that expectations play a
large role in what listeners hear in backward speech. For
example, Vokey and Read listened carefully to recordings of
Jabberwocky and the 23rd Psalm played backward. They identified
12 areas in the tapes where strings of tones suggested spoken
messages (such as "saw a girl with a weasel in her mouth). Vokey
and Read them asked their listeners to try to hear one of the
specific messages that they "discovered." Only half of the
messages listeners were asked to listen for were actually "in"
the backward recording they were hearing (the other half were
from the other tape). Listeners were likely to hear the messages
for which some evidence was actually present in the tape they
were hearing. They did not hear the messages that had been
"found" in the recording that was not played. 
test the effect of expectation, Vokey and Read then asked
listeners to try to hear other messages "discovered" in the
backward recording they were asked to listen to. For example, if
subjects had listened for "saw a girl with a weasel in her
mouth" from Jabberwocky, they now listened for another phrase
that there was evidence for--"I saw Satan." Participants were
first asked if they had heard this message on their previous
trials with the passage. Most had not, but they could hear it
once they had been told to listen for it. Changing the mental
set changed what messages people "heard" in backward speech.
This type of biased listening is similar to a reverse
speech analyst listening to backward speech for a
message that he or she "knows" is there. For example, a
therapist listening to tapes from a child who has been sexually
abused knows to listen for reverse speech messages
relating to the abuse. Anything in the backward speech
that can be heard as sexual (or that can be interpreted as a
metaphor relating to sexual acts) could then be detected. Other
"messages" would be ignored.
Thorne and Himelstein further demonstrate how mental set can
alter what a person hears in backward recordings.  They
played rock-and-roll songs backward for listeners. One group was
told to record their reactions to the music. A second group was
told to write down any words they heard in the music. A third
group was told to listen for satanic messages. For the group
recording its reactions, 5% of what they thought they heard was
satanic; for the group listening for words, 18% of what they
thought they heard was satanic; for the group listening for
satanic messages, 41% of what they thought they heard was
satanic. People's task set determined whether or not they
interpreted a message as satanic.
Another factor in "wishful listening" is the belief in the
phenomenon itself. Benoit and Thomas showed that listeners who
believed in subliminal perception were more likely to "hear" a
subliminal message in a jazz composition than were nonbelievers
(there was no subliminal message in the music).  Moreover,
believers' moods changed in the direction suggested by the
experimenter as a result of listening to the music (e.g., if
they expected the music to induce a positive mood, their mood
became more positive). Nonbelievers' moods did not change as a
result of listening to the music.
The results of these studies suggest to us that what people
"hear" in backward speech is a product of their belief in
the phenomenon and their expectations about the content of
whatever messages they are listening for. True, something is
probably there in the signal that can be interpreted by the
listener based on these expectations, but there is no evidence
to show that what is in the stimulus is really "in" the stimulus
and not merely in the imagination of the listener.
The second reason we doubt the claim that speakers embed
messages in reverse speech deals with Oates'
claims about the phenomenon itself. For example, Oates claims to
have analyzed conversations taking place in reverse
speech. These conversations are based on the listener's
comprehension of the meaning of the backward message, which is
not possible. As an example, consider a conversation Oates had
with a reporter. Oates asked the reporter to lie about his age.
When analyzing the reversals, Oates claims to find the reporter
uttering his true age in reverse speech. Oates'
response (also in reverse speech) contains this
true age. This is supposed to show that Oates unconsciously
perceived the reporter's age and echoed it back. Other backward
"conversations" in Oates' book have listeners responding to
utterances that are as much as eight words long (e.g., "Might as
well keep saying that I'm filthy."). This is clearly beyond the
capabilities of an unconscious that cannot meet the two word
challenge. We propose th at Oates' ability to analyze reverse
speech to produce a result that is not possible
demonstrates that it is all wishful listening.
Our discussion of these issues does not conclusively prove that
the first claim of the reverse speech hypothesis
is wrong. However, it does highlight the fact that supporters of
the hypothesis have a great deal of work ahead of them if they
want to "prove" that it is true. At this point; the principle of
Occam's razor--if two explanations exist for a phenomenon,
choose the simpler explanation--can be invoked to rule out the
claim that listeners embed backward messages in their speech.
Well understood mechanisms already account for speech
production. Layering on a second message produced by different
processes introduces unnecessary complexity to the theory and a
high standard of support is required for such a hypothesis to be
WHY SHOULD WE CARE?
this point we feel compelled to remind readers why we think this
hypothesis is worth testing. Outside of the world of academia,
ideas can gain support on the basis of anecdotal reports. Simply
appearing on television and repeating an idea to a credulous
audience can be sufficient to give that idea momentum and help
it work its way into the popular consciousness (Oates claims to
have given more than 200 media interviews). For example, the
idea that subliminal messages in advertising will exert an undue
influence on consumers started with a report of a (possibly)
fictitious experiment in a movie theater where participants were
told to "eat popcorn." This idea has been expanded upon by Key
and is now one of the "facts" about psychology that everyone
knows,  It was, in part, responsible for the Judas Priest
trial regarding backward messages in rock albums.
the extent that an idea is an interesting diversion, it makes no
difference whether its claims are true or false. However, when
an idea is used in an applied setting, then its claims should be
held up to scrutiny. The reverse speech hypothesis
is being pushed as offering new insights into therapy.
Psychologists are being encouraged to undergo reverse
speech training so that they can incorporate it into their
interactions with clients. Dawes makes a strong case that
therapeutic interventions in psychology should be based on the
results of scientific experiments and not on the claims of a
practitioner who feels strongly that the intervention works.
 In this case, all of the evidence suggests that the
reverse speech hypothesis is wrong.
Oates also advocates the use of reverse speech in
investigative work. He claims to have been consulted in at least
one criminal investigation. In his list of endorsements, Oates
cites an attorney and the National Private Investigator's
Journal. Before the reverse speech hypothesis is
used in applied settings, its validity should be thoroughly
established. This is particularly important with respect to the
judicial system where the consequences of an error can be so
severe. Not only is the well-being of individuals at stake, but
legal precedents can also be set. For example, even though Judas
Priest was not found liable, the judge's decision that backward
messages are not protected by the first amendment has been used
in other cases.
his book Oates proclaimed that "like it or not, the day of Truth
has arrived." We agree, and our data show that the truth is that
the reverse speech hypothesis is wrong.
Dr. William Langston, Ph.D. is an assistant professor of
psychology at Middle Tennessee State University. His area of
research specialization is the psychology of language, and his
primary teaching responsibility is research methods. He is the
author of nine scholarly articles and has made 12 presentations
at national or international research conferences. He is also
the author of the Research Methods Laboratory Manual (which will
be published by Wadsworth this summer and from which this
biography has been lifted). John Chris Anderson is an
undergraduate psychology major at
John Chris Anderson was an undergraduate psychology major at
Middle Tennessee State University when the paper was written. He
will pursue a Master's degree in Industrial/Organizational
psychology in the Fall of 2001.
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