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Integrative Physiological and Behavioral Science, January-March 2000, Vol. 35, No. 1, pp.
17-34.
Rev_Learning.doc
Revisiting the Learning-Without-Awareness
Question in Human Pavlovian Autonomic
Conditioning: Focus on Extinction in a
Dichotic Listening Paradigm
JOHN J. FUREDY1
BORIS DAMKE2
WOLFRAM BOUCSEIN2
1
Department of Psychology, University of Toronto, Canada
2
physiological Psychology, University of Wuppertal, Wuppertal, Germany
Abstract—-Numerous studies have indicated that, consistent with current "cognitive" accounts of information processing, human Pavlovian autonomic discrimination acquisition
cannot occur without awareness of the CS-US relationship. However, extinction studies
have suggested that awareness is not necessary, findings that, in information -processing
terms, have been explained by assuming that the processing by the extinction stage is
parallel (automatic) rather than serial (controlled). This explanation was tested in an 80subject study. The first, acquisition phase was a standard semantic differential conditioning
arrangement with a 96-db white noise as US, and a "long" CS-US interval of 8 s, with ten
trials each of CS+ (paired with US) and CS- (unpaired) trials. In extinction (USs omitted),
in order to obtain non-autonomic indices of processing and thereby test the
information-processing account of "unaware" autonomic conditioning during extinction, a
dichotic listening task was implemented, with the CSs presented in the unattended channel
(ear), while the subject had to perform a semantic differential reaction task in an
attended-to channel (other ear). In early extinction, the electrodermal response occurring at
an interval of 9-15 s after CS onset (i.e., following placement of the US during acquisition)
and the finger-pulse-volume response occurring at an interval of 4--I1 s after CS onset both
showed reliable conditioning, but reaction-time and subjective-report data for the recognized critical words indicated serial rather than parallel processing of the CSs during
extinction.
Key Words—-learning without awareness, human Pavlovian long-interval discrimination
conditioning, acquisition vs. early extinction, information-processing accounts, serial versus parallel processing, electrodermal responses.
Introduction
THE LEARNING-WITHOUT-AWARENESS phenomenon has long been of central interest to students of conditioning. In the heyday of S-R behaviorism that was the dominant Zeitgeist
until the late fifties, awareness was considered a mere epiphenomenon of conditioning, and
reports of learning-without-awareness (of the CS-US or operant-reinforcer relationship)
phenomena abounded in both classical (Pavlovian) and operant conditioning. In many of
these studies awareness was measured crudely, so that its apparent absence could well
Address correspondence to: John J. Furedy, Ph.D., Department of Psychology, University of Toronto, 100 St.
George Street, Toronto, Ontario M5S 3G3, Canada. E-mail: furedy@psych.utoronto.ca
Integrative Physiological and Behavioral Science, January-March 2000, Vol. 35, No. 1, 17-34.
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FUREDY, DAMKE, AND BOUCSEIN
have been due simply to measurement insensitivity. In contrast, the currently dominant
Zeitgeist assigns conditioning the merely epiphenomenal role, and awareness the exclusive
causal one. Perhaps the apogee of this form of cognitivism applied to Pavlovian conditioning is represented by the authoritative assertion that Pavlovian conditioning is "now described as the learning of relations among events" (Rescorla, 1988: 151, our emphasis).
Clearly, in this view, learning without awareness is almost a logical impossibility. Essentially, this cognitive approach views the organism in terms of the information-processing,
computer metaphor, so that conditioning is "described as" the analysis of (CS-US) contingencies, or of "the relations between events," and the organism is seen, essentially, as an
computer-like analyzer of contingencies.
However, to those for whom the issue of the role of awareness in conditioning raises
questions of an empirical sort rather than more or less convenient metaphors, human
Pavlovian autonomic conditioning (HPAC) is of particular interest. This is so because the
dependent variable (usually the electrodermal response [EDR]) is unavailable to consciousness, and because CS-US contingency awareness can be readily measured independently of EDR conditioning either following the conditioning experiment (e.g., Baer and
Fuhrer, 1968), or, more accurately, during the experiment (e.g., Furedy and Schiffmann,
1973). An additional reason for special interest is that when the US is aversive (e.g.,
electric shock or loud noise), there is the possibility that the conditional EDR reflects the
learning of an emotional non-computer-like process, i.e., fear.
By the early 1970s there was extensive evidence to indicate that, at least in acquisition,
awareness of the CS-US relation was necessary for the discrimination form of this conditioning—mainly because autonomic dependent variables like the EDR are grossly affected
by individual differences, most current forms of autonomic conditioning are of the discrimination sort, i.e., where both CS+ (associated with the US) and CS- (not associated
with the US) are presented to all subjects, and where conditioning is defined as occurring
when responding to CS+ significantly exceeds responding to CS-(CS+>CS-). For example, a review of the acquisition literature by Dawson (1973) indicated that all prior
reports of apparent unaware conditioning were easily accounted for in terms of an
insensitivity of the measures of awareness employed, and that, in terms of the ques tion raised in the title of his paper, classical conditioning could not occur without
contingency learning.
It bears emphasis that demonstrations of necessity, no matter how convincing, do not
permit an inference of causality, for which a demonstration of sufficiency is minimally
required. Dawson's (1973) demonstration of necessity was accompanied in the same journal by Furedy's (1973) refutation of sufficiency, in a review that presented evidence of
such dissociations between awareness and conditioning as the lack of any correlation
between awareness of the CS-US relations and the extent of discriminative autonomic
conditioning. A resolution of the apparent conflict between the two reviews was offered in
the "necessary-gate" hypothesis (Dawson and Furedy, 1976), but, as detailed most recently
by Furedy and Kristjansson (1996), this resolution itself is ambiguous concerning whether
awareness is not sufficient but nevertheless important for conditioning, or whether it is a
relatively unimportant factor in the acquisition of autonomically controlled and apparently
useless (i.e., without a clear function) responses such as the EDR, as well as of more
potentially useful responses like heart-rate deceleration (Furedy, 1992).
For those who would argue that awareness is important for acquisition, one problem is
that the experiments demonstrating necessity with normal human subjects have employed
THE LEARNING-WITHOUT-AWARENESS QUESTION IN HUMAN PAVLOVIAN CONDITIONING
19
preparations where the CS-US contingency is masked (e.g., Baer and Fuhrer, 1968) because, otherwise, almost all subjects quickly become aware of the CS-US contingency.
Masking is an appropriate methodological device for assessing necessity, but it may beg
the question of importance. A thought experiment proposed by Furedy and Kristjansson
(1996) illustrates this point. In that hypothetical experiment, the CS+/CS- difference is one
of wavelength, where the stimuli are so desaturated that, for half the subjects, the CS-US
contingency is effectively masked. The usual result that only those subjects who were
aware of the CS-US contingency (for which, obviously, CS+/CS- discrimination was
necessary) showed discrimination acquisition EDR conditioning would demonstrate only
the necessity of wavelength discrimination under these masked conditions, but not the
importance of CS-US awareness in conditioning. Nevertheless, the fact that the evidence is
so clear on the necessity of awareness for acquisition conditioning has led most current
students of conditioning to follow Brewer's (1974) lead, and ascribe to awareness an
influence of considerable importance, if not one of sole causality or as being the terms in
which conditioning is to be "described" (Rescorla, 1988).
In contrast, the evidence on the relation between awareness and (early) extinction has
not provided clear support for even the relatively weak necessity hypothesis. It is true that
early reports of conditioning in early extinction by unaware subjects by Diven (1937) and
Haggard (1943) were shown to have methodological flaws by Dawson (1973). This is not
surprising, because these early reports would also have constituted examples of unaware
acquisition conditioning. However, another requirement for the necessity of awareness is
that, once subjects become aware that the CS and US are no longer associated, autonomic
discrimination conditioning should also disappear. This has not been the case, especially
with "prepared" CSs of the sort studied by Oehman and his associates (e.g., Oehman et al.,
1976) and have led to the suggestion that at least certain sorts of extinction do not operate
according to cognitive CS-US contingency awareness, but rather according to noncognitive S-R processes (e.g., Oehman, 1979).
A version of this view has been formulated in cognitive models of human information
processing (Posner and Boies, 1971; Shiffrin and Schneider, 1977). These models draw a
distinction between parallel and serial processing, and apply, respectively, the terms "automatic" and "aware" to the two sorts of processing. Applied to conditioning, parallel processing is clearly of the S-R learning sort, for which awareness of the CS-US contingency
is not necessary, whereas serial processing involves "the learning of relations between
events" (Rescorla, 1988) for which contingency awareness is not only necessary, but also
very important.
The information-processing position also asserts that, to be established, automatic information processing must be preceded by training. Applied to conditioning, repetition of
CS-US trials constitutes training, and, in the typical conditioning preparation these training
(CS-US acquisition trials) should produce a transition from serial to parallel processing.
Accordingly, during early extinction, awareness may not be necessary for the CS+>CSautonomic conditioning phenomenon, if sufficient training has produced a shift from serial
to parallel processing during acquisition.
Some preparations like that of eyelid conditioning allow the use of a large number of
acquisition trials, with asymptotic responding to CS+ being reached and maintained for as
many as 100 acquisition trials. By this stage, the shift from serial to parallel processing can
safely be assumed to have occurred, thus permitting a clear test of the awareness-necessity
assumption for extinction eyelid conditioning. However, autonomic responses like the
EDR allow only about eight CS-US acquisition trials, before responding begins to habitu-
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FUREDY, DAMKE, AND BOUCSEIN
ate (see e.g., Kimmel, 1966), so the method of using a large number of acquisition trials to
guarantee the serial-to-parallel processing shift is not available.
A methodological alternative is to test for the presence of the processing shift rather
than guarantee its presence. A preparation which appears to be suited for this purpose is
that of a dichotic listening task (e.g., Corteen and Wood, 1972; Corteen and Dunn, 1974)
which can be superimposed on the conditioning "task" (i.e., discriminating between CS+
and C-) during acquisition or, as in the present case, during extinction. Briefly, after
subjects had engaged in the acquisition phase of a semantic differential conditioning task
with CSs (words in two categories) presented binaurally through earphones, the extinction
period (a "new task" for the subject) was introduced, in which the CS words without the
noise US would be presented in one ear. Simultaneously, in the other ear (to which alone
subjects were instructed to attend), there would be presented new words (from two different categories) which subjects would have to discriminate by minimal reaction time (RT)
to press a button whenever the word fell into one category (fruit) rather than the other
(vegetable).
The shift from serial to parallel processing is assumed to occur if there is no interference
between the two tasks, namely CS and RT discrimination during the binaural, dichotic
phase. It will be noted that because this issue can be assessed independently of whether
early extinction has yielded the learning-without-awareness phenomenon (i.e., autonomic
discrimination in the absence of a belief in differential CS+/CS- CS-US contingency), it
becomes possible to provide an empirical, and non-circular test of the serial-to-parallel
processing account of the early-extinction autonomic-learning-without-awareness phenomenon.
Specifically, the account was tested by determining whether two hypotheses deduced
from the account were confirmed. The first hypothesis was that there would be no performance (reaction-time) deficit in the attended channel when, in the unattended ("parallel")
channel a CS+ rather than a CS- was presented. This hypothesis follows from the assumption that the early-extinction CS+>CS- autonomic effect is automatic and "parallel" to the
reaction-time task in the attended channel.
The second hypothesis was that, in a post-experimental questionnaire, subjects would
not report having recognized the critical (CS+) words in the unattended channel. This
hypothesis also follows from the assumption that the processing is parallel rather than
serial during early extinction.
The main dependent autonomic conditioning variable here, as in most studies, was the
EDR. The relatively long (8-s.) CS-US interval employed allowed separation of CSelicited EDRs into the first-interval response (FIR-—-occurring 1-5 s. following CS onset),
second-interval response (SIR—-occurring 5-8 s. following CS onset), and thirdinterval response (TIR-occurring, on CS-alone extinction trials, 9-15 s. following CS
onset). Different mechanisms have been ascribed to these latency-specified EDRs (for an
overview, see Boucsein, 1992). The most common view (e.g., Stewart et al., 1961) holds
only the SIR to be a "true" CR. reflecting anticipation of the US, with FIR being merely an
orienting reaction to the CS (analogous to the short-latency, "alpha" response in eyelid
conditioning, which habituates rather than increases as a function of CS-US conditioning
trials—-see also Prokasy and Ebel, 1967; Furedy and Poulos, 1977), and the TIR being an
orienting reaction to the omission of the US (which represents a novel stimulus leading to
the reinstatement of the orienting reaction-—see also Sokolov, 1960).
These hypotheses about mechanisms, however, have not always been confirmed by the
actual EDR results. For example, it has been frequently observed (e.g., Furedy and
THE LEARNING-WITHOUT-AWARENESS QUESTION IN HUMAN PAVLOVIAN CONDITIONING
21
Schiffmann, 1973; Oehman et al., 1976) that the SIR fails to show any reliable evidence
for the basic discrimination conditioning CS+>CS- outcome, which makes further speculations about the conditioning mechanisms that underlie the conditional SIR rather moot. It
appears necessary to observe, empirically, in each study which of the EDR components
show evidence for the basic acquisition CS+>CS- conditioning effect, and then of the
same effect during early extinction. We took this approach here, and also recorded the
finger pulse volume response (PVR).
The PVR is another autonomically controlled response which behaves similarly to the
EDR in discrimination conditioning studies (e.g., Furedy and Schiffmann, 1973), except
for having a somewhat longer latency (so that, over an 8-sec CS-US interval, only one
response can be observed). Finally, heart-rate (HR) was measured on a beat-by-beat basis.
As detailed elsewhere (Furedy and Poulos, 1976), with loud-noise and shock USs (though
not with negative tilt), the topography of the conditional HR response is multiphasic and
complex, and the discrimination conditioning phenomenon itself is less than robust. Further analyses of the HR data would proceed only if there was a significant difference
between mean post-CS+ and post-CS- HR trends during acquisition.
Finally, the restrictive aims of our experiment bears some emphasis. Our concern is
specifically with human Pavlovian autonomic conditioning with aversive USs like shocks
and tones, rather than with other preparations, or ones with animal subjects. Moreover, the
dichotic listening task is employed as a tool to manipulate awareness under conditions
where the parallel vs. serial distinction from the informational-processing approach seems
to apply. We are not concerned with other interesting questions about the dichotic- listening task in other preparations (see, e.g., Holender, 1986), or such other parameters of
human Pavlovian autonomic conditioning such as lateralization (e.g., Hugdahl, 1996).
Method
Subjects
Subjects (Ss) were eighty German-speaking undergraduates . (thirty-six male, forty-four
female) between eighteen and forty-two years (mean age 26.64 years). The Ss were paid
for their participation at the University of Wuppertal Physiological Psychology laboratory.
Stimulus Materials and Apparatus
The stimulus materials consisted of pairs of two-syllable German words (e.g., "lion"
and "zebra") that belonged, respectively, to the four semantic categories of buildings,
animals, fruits, and vegetables. These words, taken from a four-track TEAC tape recorder,
temporarily stored on a sound card in the 80386 PC, and presented over Beyer Dynamics
headphones were used both for the CSs (building and animal categories) and for the
concept-identification task that employed reaction stimuli (RSs) to which subjects had to
either react (RS+) or not react (RS-) as a function of the fruits/vegetable category distinction. The 96-dB white noise (employed for the aversive US) was generated by a Bruel and
Kjaer type 1405 noise generator.
For electrodermal recording, Beckman Ag/AgCl-electrodes (0.6 cm2) and Unibase electrode paste with 0.9% NaC1 concentration were used, and the electrodes were attached to
the thenar and hypothenar sites of the non-dominant hand with doubleside adhesive tape.
The electrodermal responses (EDRs) were amplified with a coupler developed in the
22
FUREDY, DAMKE, AND BOUCSEIN
Wuppertal laboratory (Boucsein, 1992), and were expressed in units of micro Siemens
change. Respiratory activity was monitored by means of a belt with a piezo electric
transducer to eliminate EDRs that were obviously the result of gross respiratory changes,
i.e., of respiratory artifacts; less than 1% of EDRs were eliminated for this reason.
Finger pulse volume was measured using the photoplethysmograhic method on the left
index finger with a coupler developed in the Wuppertal laboratory, using the back scat tered method described by Brown (1967, Fig. 2.3).
For heart-rate, the electrocardiogram was recorded by using an Einthoven-II (right arm/
left foot) lead arrangement, with Beckman Ag/AgC1 Electrodes (0.6 cm2) and Hellige
electrode paste, and the interbeat intervals were employed to derive heart -rate. All data
were recorded and amplified by a Nihon-Kohden polygraph and digitally stored on a
second 80386 PC.
Procedure
The S was comfortably seated in a sound-attenuated and air conditioned chamber (2021 C~ 45 percent relative humidity). After E had attached the electrodes and the respiration belt, he told S that during this first phase of the experiment, the S would hear words
and a loud noise through the earphones, which were then put on the S. The subject's task
was simply to listen, sit reasonably still, and breathe fairly regularly. After a two-minute
period of baseline recording, the acquisition phase of the experiment began.
The acquisition phase comprised a twenty-trial discrimination conditioning arrangement
with an intertrial intervals varying unsystematically between 25 and 45 s. The ten CS+ (paired
with the US, a l-s, 96-dB [A] white noise, the onset of which occurred 8 s after CS+ onset) and
ten CS- (unpaired with the US) trials were interspersed throughout the 20-trial series.
The buildings-and-animals categories were employed to vary CS valence, and for each
of four groups of 20 Ss, one word from one category (e.g., station) served as CS+, while
the other three words (i.e.. barn, lion. and zebra) served as CS-. The three CS- words were
distributed randomly in the ten-trial acquisition CS- trial sequence with the restriction that
no word occur more than four times. This arrangement controls for the nature-of-stimulus
effect in interpreting the valence (conditioning) contrast (i.e., CS+>CS- outcome interpretable in terms of valence rather than differences between words).
At the end of acquisition the earphones were removed, and S was told that for the next
task "you will again hear words over the earphones. However, you should pay attention
only to the words coming through the right (or left) side." For half the subjects in each of
the four nature-of-CS+ groups formed during acquisition, the right side was the attended-to
channel, while for the remainder the attended-to-channel was on the left side. The instructions to S continued, "On this side you will work on two semantic categories, vegetables or
fruits. If you hear a fruit word, press the button as quickly as possible." The valence of
these reaction time (RT) trials in the attended channel, varied between RT+ (press button)
and RT- (not press button). The earphones were then put on, and a twenty-trial extinction
phase was given (intertrial intervals as in acquisition), comprising interspersed trials of
five each of the following compounds, with RT and CS being presented, respectively, in
the attended and unattended ear (channel): RT+/CS+, RT-/CS+, RT+/CS-, and RT-/CS-.
In addition to the physiological recordings, reaction time was recorded, in ms, from CS
onset to the button press on trials containing an RT+ component. Finally, after the completion of extinction, a twenty-item recognition test was administered to test the number of
unattended (CS) words that were recognized.
THE LEARNING-WITHOUT-AWARENESS QUESTION IN HUMAN PAVLOVIAN CONDITIONING
23
Data Analysis
Following Prokasy and Ebel (1967), EDRs were (manually) scored as first interval
response (FIR, I to 5 s after CS onset), second interval response (SIR, 5 to 8 s after CS
onset), and third interval response (TIR, 9 to 15 s after CS onset). For each time window,
the EDR magnitude was computed, scoring a zero amplitude for those windows where no
responses occurred (see Boucsein, 1992). The value of 0.01 micro Siemens was employed
as the criterion for non-zero amplitude.
For the finger pulse volume, the response (PVR) was defined as the algebraic difference
(expressed in percent units) between the largest vasoconstriction occurring between 4
and 8 s (acquisition) or 4 and 11 s (extinction) after CS onset, and the mean level for 5 s
prior to the onset of that CS as the baseline comparison l; six subjects were excluded from
the PVR analyses, because of movement artifacts (4) and other technical apparatus
problems (2). For heart-rate (HR), every beat for 8 s after CS onset was expressed as the
algebraic difference (in beats per min.) between HR during that beat, and the mean HR
for 5 s prior to the onset of that CS as the baseline comparison.
The data were analyzed separately for acquisition and extinction, employing mixed
three-factorial ANOVAs. The two within-subject factors were "trial number" (1-10) and
"valence" (CS+/CS-). The eight-level between-factor of "word/channel" resulted from the
permutation of CS+ word in acquisition (CS+ as station, barn, lion, and zebra) and the
channel (right vs. left ear) in which the attended-to concept formation task was presented
during extinction. As expected, these counterbalanced influences did not yield any significant
main or interaction effects in the analyses (see Furedy, 1967 for analysis for interactions of
counterbalanced factors). Conservative Greenhouse-Geisser corrections were applied throughout by setting numerator df values at unity; the criterion for significance was set at p < 0.05.
Results
For this report, which is focussed on the relation between awareness of the CS -US
relation and autonomic (early) extinction performance, the primary interest in the acquisition data was to determine which autonomic dependent variables yielded reliable evidence
for conditioning, i.e., the CS+>CS- effect. Those variables that did so were then examined
during early extinction. An exception to this rule was the treatment of the electrodermal
TIR, which, with a 100% reinforcement schedule during acquisition (as was done here),
can only be examined during extinction.
Acquisition
The mean electrodermal responses to CS+ and CS- during acquisition for FIR, SIR, and
TIR (the unconditional response (UR) to the US in the case of CS+, and an estimate of
non-stimulus-elicited, spontaneous or "operant-level" responding in the case of CS-) are
shown in Figure 1. Figure 2 summarizes the same data to show trial-by-trial (in blocks of
successive pairs of trials) developments.
As suggested by Figure 1, the conditioning (CS+>CS-) effect emerged as significant in
both FIR and SIR, F (1,72) = 12.3 and 15.19, respectively, p < 0.001. This constitutes clear
evidence for acquisition discrimination conditioning in these two pre-US components of
the EDR; the TIR CS+>CS- effect, of course, for which F (1,72) = 29.46, p < 0.001,
reflects merely the greater potency of the US in eliciting EDRs on CS+ acquisition trials.
24
FUREDY, DAMKE, AND BOUCSEIN
FIG. 1. Mean skin conductance response magnitudes during acquisition.
Figure 1 data also suggest differences in EDR average magnitudes as a function both of
eliciting stimulus (CS vs. US), and of latency of occurrence (SIR vs. FIR). Statistical
analyses confirmed these trends. The mean US-elicited EDR (UR-—TIR to CS+ on right in
Fig. 1) significantly exceeded the FIR elicited by CS+ (CR—-FIR to CS+ on left of Fig. 1),
F (1,72) = 6.88, p < 0.05. However, the latency-of-occurrence effect was even clearer
statistically. The FIR to CS+ (i.e., the shorter-latency CR) significantly exceeded the SIR
to CS+ (i.e., the longer-latency CR), F (1, 72) = 132.7, p <0.001. Finally. the SIR to CSnot only failed to significantly exceed spontaneous response levels (as measured by TIR to
CS-), but was even significantly lower than this "operant" level, F (1, 72) = 4.43, p < 0.05,
which suggest that the requirement of CS "neutrality" for the unpaired CS- (which is
fulfilled for the conditional eyelid and salivary responses, but not usually for the EDR),
was fulfilled for the SIR in this study.
The trials-by-trials summary of the same data in Figure 2 also suggest that the SIR was
superior to the FIR with respect to other "marks" of conditioning that are supplemental to
the main criterion of CS+>CS-, but are nevertheless thought to be important by some
students of the phenomenon. So while the FIR functions (top panel of Fig. 2) simply
appear to decrease over trials towards the same asymptote (i.e., habituation), the SIR
functions (middle panel of Fig. 2) exhibit the sort of interaction expected on the basis of
differential reinforcement of CS+ and CS- over trials. However, although suggestive, the
trials x valence interaction in the SIR did not reach the 0.05 level of significance, F (1,
648) = 3.06, p < 0.1.
THE LEARNING-WITHOUT-AWARENESS QUESTION IN HUMAN PAVLOVIAN CONDITIONING
FIG. 2. Mean course of skin conductance response magnitudes during acquisition.
25
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FUREDY, DAMKE, AND BOUCSEIN
Fig. 3. Mean course of the finger pulse volume response magnitudes during acquisition.
Another supplementary "mark" of conditioning that is generally not achieved in autonomic preparations is an increase (or at least the absence of decrease) over trials of CS+
presentations during acquisition. By this criterion, the FIR CS+ function (top panel of
Fig. 2) failed miserably, the decline over trials being highly significant F (1, 648) =
10.6, p < 0.001. The same decline is evident in the TIR to CS+ (bottom panel of Fig.
2), which is really the UR to the US, and that also was highly significant with a
higher F value, F (1,648) = 15.3, p < 0.001. Such marked habituation is typical of EDR
conditioning studies (which may be one reason why performance over trials is seldom
shown), and the UR habituation appears to refute the notion of distinguishing between
orienting responses (to CSs) and defensive responses (to USs) on the basis of whether
habituation is present or absent, respectively. In contrast, the SIR to CS+ (middle
panel of Fig. 2) snowed no reliable decrease over trials, even if the function is still
different from the "classic" eyelid function of a negatively accelerated asymptotic
increase over trials, in summary, then, the SIR, though obviously smaller in magnitude
than the FIR, yielded as clear evidence for acquisition conditioning in terms of the main
criterion of CS+>CS-, and also outperformed the FIR in terms some other
supplementary "marks" of conditioning such as pre-training CS neutrality and failure of
CS+ function to habituate over reinforced acquisition trials. As noted in the introduction,
these SIR results are in marked contrast to most of the earlier literature, where SIR often
failed even to yield the basic CS+>CS- phenomenon. For the vasomotor PVR, a
significant valence (CS+>CS-) effect emerged, F (1,66) = 6.90, p < 0.05, but neither
the valence x trials interaction nor the trials effect itself reached significance.
THE LEARNING-WITHOUT-AWARENESS QUESTION IN HUMAN PAVLOVIAN CONDITIONING
27
FIG. 4. Mean skin conductance response magnitudes daring early extinction (~riai bIocks I and 2).
Figure 3 summarizes the results, and suggests an (insignificant) interaction that "looks"
orderly, i.e., especially in the third and fourth trial blocks, where both the CS+/CSdifference and the CS+ function appear to increase. However, these are merely insignificant trends. What is clear, in contrast to the EDR FIR and TIR acquisition functions, is that
there is no evidence for vasomotor habituation. This electrodermal/vasomotor difference
has been reported before (e.g., Furedy, 1968), and is difficult for those accounts (e.g.,
Sokolov, 1960) according to which the EDR and PVR are both components of the habituating orienting reaction (OR).
No significant effects emerged for HR.
Early Extinction
Figure 4 summarizes the early-extinction (first and second two-trial extinction blocks)
results for the electrodermal FIR, SIR, and TIR. It will be recalled that acquisition testing
for TIR is not possible in this preparation, but evidence of acquisition conditioning for the
two pre-US components (FIR and SIR) had been obtained.
The FIR early-extinction results in Figure 4 (left) suggest a first-block CS+>CS- effect
that disappears by the second block, but a blocks (lst vs. 2nd) by valence (CS+ vs. CS-)
28
FUREDY, DAMKE, AND BOUCSEIN
FIG. 5. Mean finger pulse volume response magnitudes during early extinction (trial blocks 1 and 2).
ANOVA failed to yield any effects that even approached significance, Fs < 1.2. The SIR
results (Fig. 4, center) do not even suggest an early-extinction conditioning effect, with
CS- responding during the first block appearing to exceed that to CS-. This reversed CS>CS+ SIR effect was significant, with the blocks by valence ANOVA yielding a main
effect for valence, F (1, 72) = 4.69, p < 0.05.
In contrast to these FIR and SIR early-extinction results, the TIR, as suggested by
Figure 4 (right) showed clear evidence for early-extinction conditioning. The valence x
blocks ANOVA yielded significant effects for valence (CS+>CS-), blocks (decline over
blocks), and a valence x blocks interaction (CS+/CS- difference declining over blocks), F
(1, 72) = 36.7, 16.9, and 6.18, respectively, p < 0.02. It will be noted that the F value for
the valence effect exceeded the acquisition F values for valence of the FIR and SIR during
acquisition (Fig. 1).
Figure 5 shows the early-extinction results for the vasomotor PVR. As for the electrodermal FIR (Fig. 4, left), the trends indicate evidence for early-extinction conditioning,
but, in contrast to the FIR results, the inferential PVR statistics were unequivocally supportive, with both the valence x blocks interaction and valence effects being significant, F
(1, 66) = 22.3 and 9.48, and p < 0.001 and 0.01, respectively.
Accordingly, the results showed clear conditioning in early extinction for the electrodermal TIR (Fig. 4, right) and the vasomotor PVR (Fig. 5). This allowed the two hypotheses
derived from the information-processing position (that these cases of early-extinction con-
THE LEARNING-WITHOUT-AWARENESS QUESTION IN HUMAN PAVLOVIAN CONDITIONING
29
FIG. 6. Mean reaction times during early extinction (trial blocks 1 and 2).
ditioning involved parallel rather than serial processing) to be tested with the reaction-time
(RT) and recognition-test data.
The relevant RT results are summarized in Figure 6. As suggested by the trends, a
valence x blocks ANOVA yielded a significant valence effect, F (1, 72) = 15.36, p <
0.001, with longer reaction times on CS+ than CS- trials. This constitutes clear evidence
for interference from the (unattended) CS channel with the (attended) RT channel, and
hence indicates serial rather than parallel processing.
The recognition test data (based on the twenty-item test) also yielded clear evidence for
serial processing in that subjects identified CS+ and CS- words, respectively, 75 percent
and 15 percent of the time, a difference that was significant by a non-parametric test, Chisquare = 485.4, p < .001.
The electrodermal early-extinction data (Fig. 4) displayed some other features concerning which the information-processing theoretical framework is silent, but which are of
interest to students of human autonomic conditioning. One such feature emerges if one
compares early-extinction EDRs to CSs (Fig. 4) with responding during acquisition (Fig.
1). Even though, in extinction, CSs were delivered in an unattended channel, the FIRs to
these unattended CSs (Fig. 4, left) significantly exceeded not only the acquisition CS elicited FIRs (Fig. 1, left), F (I. 72) = 20.2, p < 0.001, but even the US-elicited TIRs (Fig.
1, right, CS+ column). The inferential statistics calculated for the comparison involving
responding to the unattended CSs and the US-elicited responses (TIRs) comprised separate
30
FUREDY, DAMKE, AND BOUCSEIN
comparisons of unattended CS+ and CS- trials with the US-elicited TIR trials, and yielded
F values of 16.9 and 18.8 for unattended CS+ and CS- trials, respectively, p < 0.001.
On the other hand, the same early-extinction/acquisition comparison with SIRs (center
of Figs. 1 and 4) showed the opposite trend, which was also highly significant, F (1, 72) =
17.5, p< 0.001.
The increase in FIR (but not SIR) to the ("unattended") CSs during extinction is almost
certainly a result of the newly introduced RT task, and it is even possible, because of the
relatively long onset latency of the autonomically controlled EDR compared to motorcontrolled responses like reactions, that the button press itself was responsible for the
augmented early-extinction, CS-elicited FIRs. To test this possibility, a 2 x 2 ANOVA was
performed on early-extinction FIRs with valence of the CS (CS+ vs. CS-) and valence of
the RT (RT+ vs. RT-, where the button was pressed only on RT+ trials) as the two
factors. Neither the two main effects nor their interaction approached significance, F (1,72)
< 2.50, p> 0.1.
Discussion
The main focus of this study was on early-extinction conditioning (CS+>CS-) effects
obtained in human Pavlovian autonomic conditioning with aversive USs like shocks or
loud noises, when subjects are instructed that (following acquisition) only CSs and not
USs would be presented. Reliable evidence for such early extinction conditioning effects
were obtained in the electrodermal third-interval response (TIR) that follows placement of
the US during acquisition (see Fig. 4, right), and for the vasomotor PVR (see Fig. 5).
These apparent instances of awareness not even being necessary for (earl y-extinction)
autonomic conditioning have recently been explained by information-processing accounts
in terms of the distinction between parallel and serial processing. These accounts, specifically, imply that information processing during such early extinction should be parallel
rather than serial. However. contrary to this implication, both the RT results on the dichotic listening task (see Fig. 6), and a later memorial recognition test (see recognition test
results above of 75 percent and 15 percent, respectively, for CS+ and CS-), indicated that,
in information-processing terminology, the CSs were processed in a serial rather than
parallel fashion. These autonomic data, then, are inconsistent with information-processing
accounts of early-extinction, "contrary-to-awareness" (by instructions) conditioning.
Although the results constitute a relatively unequivocal refutation of the
information-processing approach to human Pavlovian autonomic conditioning, an approach that has been formulated in terms of the distinction between parallel and serial
processing, it is important to recognize that the experiment was not designed to address
several other related but different issues. One such related issue is the status of the dichotic
listening paradigm, both in terms of replicability (e.g., a failure to replicate the
Corteen-Wood study was reported by Wardlaw and Koll, 1976) and, more importantly, in
terms of whether it provides the conditions necessary to demonstrate lack of awareness
(see, e.g., Hollander, 1986, for detailed arguments and evidence that it does not). In the
present study, the dichotic-listening task was used only to provide an arrangement where,
according to the information-processing approach, the processing should be clearly be
parallel rather than serial during early extinction, where evidence of some autonomic
conditioning was obtained.
The results indicated that the processing was serial rather than parallel. The reasons
why this should have been so are not clear. One possibility is that the dichotic-listening
THE LEARNING-WITHOUT-AWARENESS QUESTION IN HUMAN PAVLOVIAN CONDITIONING
31
task that employs complex semantic stimuli may allow subjects to rapidly "shift attention"
between the two ears, where such a "shift in attention" is less likely to occur with simpler
stimuli like digits. This issue relates, however, to the viability of the dichotic-listening task
for producing truly parallel processing, rather than to the aim of the present experiment,
which was to test whether, in the presence of some autonomic conditioning in early
extinction, the processing would be parallel (as required by the information-processing
approach's account of early-extinction autonomic conditioning) or serial.
Aside from testing the two specific hypotheses derived from the information-processing
framework, another purpose of this experiment was to provide information on other reliable empirical features of human autonomic responding during both acquisition and early
extinction in the aversive conditioning preparation. On these features the modern cognitive
informational-processing framework is generally silent, or even suppressive, but knowledge of them is necessary for both understanding and controlling (i.e., making use of)
these autonomic conditioning phenomena.
To begin with the most "negative" feature of the autonomic results, the post-CS and
pre-US HR functions during acquisition failed to show any reliable changes, let alone the
basic criterion of autonomic conditioning, the CS+>CS- effect. This is actually quite a
common finding in the human HR conditioning literature that employs conventional USs
like shocks and loud noises (see e.g., Furedy et al., 1989 for a review). It is also noteworthy that it is precisely the human conditional HR response (which does not conform to the
accelerative unconditional response, and hence contradicts the "old" stimulus substitution
theory) that has served as a cornerstone for the cognitive, informational-processing approach (e.g., Rescorla, 1988). With the negative-tilt US (see e.g., Furedy, 1992) reliable
CS+>CS- HR effects of at least 5 beats per minute are obtained, but this preparation is less
favorable to information-processing accounts, with both CR and UR being decelerative in
direction, as one would expect in terms of the older, less fashionable (Rescorla, 1988)
stimulus-substitution view.
Both the electrodermal (FIR and SIR) and the vasomotor pre-US responses during
acquisition met the basic conditioning (CS+>CS-) criterion. The SIR electrodermal results
(Fig. 1, middle) are of particular interest because, as noted in the introduction, the literature
indicates that not only is the SIR much smaller than the FIR, but also this "true anticipa tory CR" often fails to show reliable conditioning, in contrast to the FIR (e.g., Oehman et
al., 1976). In our study the SIR, although much smaller than the FIR, showed at least the
same robustness as the FIR for the basic conditioning effect (both these electrodermal
measures yielded F values of over 12). Moreover, the SIR fared better than the FIR in
terms of yielding other "marks" of conditioning such as CS neutrality and a failure of the
CS+ function to simply habituate over trials. As Figure 2 indicates, not only the FIR (top
panel) but also the UR (bottom panel) was "guilty" on this count of exhibiting nonconditioning-like habituation. Still, it bears emphasis that the SIR's good acquisition
performance in this study is atypical of the literature, and that, as in that literature, the
actually responses to the CSs are very small. As such, they may be especially vulnerable to
response interference effects from the larger preceding FIRs. These relativerefractory-period effects are present in the EDR with intervals as large as 20 s, and are
inversely proportional to the inter-response period (see e.g., Furedy and Scull, 1971;
Grings and Schell, 1969). It will be noted that if a conditioning effect (CS+>CS-) appears
in the FIR, the response interference effect will work against a conditioning effect in the
immediately following SIR. On features like these of the human autonomic conditioning
preparation, cognitive information-processing theory is, of course, silent.
32
FUREDY, DAMKE, AND BOUCSEIN
In terms of "marks" of conditioning that are additional to the basic CS+>CS- effect (for
which the vasomotor F reached only the 0.05 level of significance with this relatively large
sample of subjects, in contrast to the highly significant electrodermal F values), the vasomotor PVR also fared better than the electrodermal FIR in the sense that, unlike the FIR to
CS+ (Fig. 2, top panel), the PVR to CS+ (Fig. 3) did not show habituation over trials.
However, rather than interpreting this as a mark of superiority of the PVR over the EDR
as an acquisition conditioning index, it seems more likely that we are simply seeing the
common finding that the PVR, unlike the EDR, usually does not show habituation to any
stimuli as a function of repetition (e.g., Furedy, 1968, 1969). This aspect of the vasomotor
response creates difficulties, as noted above, for Sokolovian (e.g., Sokolov, 1960) OR
theory. The relevance of this in the present context is that, as detailed elsewhere (Furedy,
1989), the Sokolovian neuronal-model disconfirmation concept is a propositional/cognitive
one, because only propositions can be confirmed or disconfirmed-—for an effect of noncognitive change on the electrodermal component of the OR, see Furedy and Scull
(1971). The failure of the vasomotor component of the OR to clearly habituate to repetition
is at least not predicted by, but is probably actually contrary to, the cognitive Sokolovian
position which, in essence, and like most current models of conditioning, views the organism as an analyzer of contingencies, or processor of information.
Turning to the results of early-extinction conditioning, which were critical for testing
the two hypotheses derived from the information-processing distinction between parallel
and serial acquisition, the first empirical point to note is that the two pre-US components
of the EDR, which provided the strongest evidence for acquisition conditioning, failed to
yield any reliable early-extinction conditioning (see Fig. 4, left and center). The SIR,
indeed, yielded a barely significant reversed (CS+<CS-) effect. These pre-US EDR components, then, proved useless for testing the hypotheses derived f rom the
information-processing accounts. In contrast, although of very small magnitude, the TIR
(Fig. 4, right) yielded highly reliable and orderly evidence for early-extinction conditioning.
On the other hand, there was one aspect of autonomic response magnitude that emerged
in a dramatic fashion, and in a way that would not be expected either on an
information-processing or most conditioning accounts. This is the fact that, during early
extinction, the CS-elicited electrodermal FIR (Fig. 4, left) not only exceeded the FIR
during acquisition (Fig. 1. left), but even the UR to the US itself during acquisition (i.e.,
TIR to CS+ in Fig. 1, right). On an information-processing account, there should have
been diminution of the FIR during extinction, given that the CSs had now been placed in
an "unattended" channel. The same diminution would seem to be predicted from most
other conditioning accounts, because of the removal of the US, and certainly neither
position would predict that the FIR to the CS during early extinction would actually
exceed the UR itself.
We were also able to rule out the possibility that the increase in early-extinction FIR
was simply an artifact of the button press that was part of the dichotic listening task
introduced at the outset of extinction. The fact that FIRs to CS trials were not significantly
larger on trials including a button press (RT+) compared to trials without a button press
(RT-) contradicts this artifactual account, and indicates that the FIR increase in early
extinction requires other explanations. These may emerge if one considers the human
subject as neither a computer-like information processor or contingency analyzer, nor an
experimental tool of students of human autonomic conditioning. Rather, during acquisi tion, many subjects are likely to be quite bored by the procedures, and their level of
THE LEARNING-WITHOUT-AWARENESS QUESTION IN HUMAN PAVLOVIAN CONDITIONING
33
attention (or even arousal) may be considerably raised to any stimuli (even CSs in an
instructed "unattended" channel) when a more interesting procedure (the dichotic listening
task) is introduced into the situation. The fact that this "atheoretical" change apparently
produces increases in CS-elicited FIRs that go even beyond the URs should warn all
human autonomic conditioning experimenters (present company included) that they have a
lot to learn about the factors which actually are influential in this preparation.
Acknowledgments
This experiment was carried out by BD in the laboratory of WB, supported by funds from the Volkswagen
Foundation, Germany (Az. II/68 759). The writeup and interpretation is primarily the responsibility of JJF. The
authors are particularly indebted to the Deutscher Akadermscher Austauschdienst (DAAD) which awarded a
visiting fellowship to JJF in the summer of 1996 to allow him to interact with his German c ollaborators for
data analysis and writeup.
Note
1. This method of measurement is probably not as sensitive as that recommended by Furedy (1968), but the
significant differences obtained with the finger-pulse-volume index suggest that it was sufficiently sensitive for
the purposes of the present experiment.
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