1 The Role of Conditioning in Sexual Arousal - Indiana University

21 Pages·2003·0.03 MB·English

by  Kinsey Institute

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The Role of Conditioning in Sexual Arousal
Heather Hoffmann
Conditioning models hold intuitive appeal for explaining the etiology of atypical
sexual arousal. The majority of treatments for sexual disorders are based on such models
(Plaud & Martini, 1999) and numerous case studies attest to the effectiveness of behavior
or response modification techniques in dealing with paraphilias (Gaither, Rosenkranz &
Plaud, 1998). It is also a common theoretical assumption that learning plays an important
role in the development of normative sexual arousal patterns (e.g., Ågmo, 1999; Hardy,
1964; McConaghy, 1987; Pfaus, Kippin, & Centeno, 2001; Roche& Barnes, 1998;
Woodson, 2002). Yet there are limited laboratory data, at least in humans, showing the
effects of learning on sexual arousal, and precisely how conditioning processes affect what
we find erotic remains unclear.
Since I am interested in the how stimuli acquire sexually arousing properties the
present chapter will focus on classical conditioning. However, a brief review of the two
standard types of laboratory conditioning paradigms and their interaction may be useful.
Classical (a.k.a. Pavlovian or respondent) conditioning involves learning about the
relationship between an initially “ineffective” cue (the CS) and a behaviorally significant
stimulus (the US) and typically results in a conditioned emotional or motivational state (the
CR). Operant (a.k.a. Skinnerian or instrumental) conditioning typically creates changes in
the frequency of (goal-directed) behavior (R) resulting from its association with reinforcing
or punishing consequences (SR). Pavlovian and instrumental conditioning can be
distinguished at a conceptual and procedural level, but in practice it has been difficult to
separate their effects (Schwartz, 1989). For example, it was once thought that the different
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types of conditioning were applicable to different classes of behavior (i.e., classical to
autonomic responses and operant to skeletal ones). However, operant procedures have
been shown to affect reflexive behavior and voluntary responding can be classically
conditioned. Procedures exist for separating the roles of classical and operant
contingencies in the control of behavior but their interactions are complex and both
processes appear to simultaneously affect any given learning situation. For example, in
sexual learning situations, stimuli that have acquired arousing properties through Pavlovian
procedures can also contribute to the approach of those stimuli. Such an explanation has
been used to describe the development of paraphilias (Junginger, 1997; McGuire, Carlisle,
& Young, 1965). An accidental pairing of a neutral object (CS) with arousal or orgasm
(US) gives the stimulus erotic value. Sexual arousal to the object (CR) elicits approach
and/or masturbation (R) that is positively reinforced by an increase in sexual arousal and
orgasm (SR). Both conditioning processes most likely contribute to acquired arousal but the
classical association appears to be at the core of such learning. In addition, the majority of
studies in both animals and humans have examined the role of Pavlovian procedures in
sexual arousal.
The laboratory evidence
Nonhumans
Pfaus, Kippen, and Centeno (2001) provide the most recent review of the influence
of learning on sexual and reproductive behaviors in a variety of species, including humans.
They concluded that classical and operant conditioning produce both temporary and lasting
changes in appetitive, precopulatory, and consummatory sexual behavior. Although Sachs
and Garinello (1978) found conditioned decreases in the time to display penile erection in
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rats, sexual arousal in nonhuman research is usually measured indirectly through changes
in latencies to engage in other sexual behaviors. For example, Domjan and colleagues
found conditioned approach, conditioned courtship, and conditioned copulatory behaviors
in male quail in the presence of CSs (e.g., colored lights, orange feathers, bird models, and
contextual cues) that were previously paired with either visual exposure to a female or the
opportunity to copulate with a female (for review see Domjan & Holloway, 1998). In male
rats, Zamble, Hadad, Mitchell and Cutmore (1985) found conditioned decreases in
ejaculatory latency in the presence of a CS (plastic tub) that had previously been paired
with exposure to a female without consummation. Kippin, Talianakas, and Pfaus (1997)
found conditioned ejaculatory preference to females scented with an odor which was
previously associated with the ability to copulate. Studies on conditioning of female sexual
arousal are less common. Gutiérrez and Domjan (1997), found increases in squatting
behavior (an index of sexual receptivity) in female quail, following the paired presentation
of a particular compartment (CS) and copulatory opportunity. Female rats engage in a
wide range of behaviors that control their sexual interactions with males, but it has yet to be
demonstrated which of, and to what extent, these behaviors are influenced by conditioning
(Pfaus et al., 2001).
Humans
O’Donohue and Plaud (1994) have provided the most recent review of the
conditioning of human sexual arousal. They concluded that while there is some evidence
for classically conditioned sexual arousal in men as measured by changes in penile
circumference or volume (e.g., Kantorowitz, 1978; Langevin & Martin, 1975; Rachman,
1966; Rachman & Hodgson, 1968), interpretation of the results are complicated by
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methodological problems. They reported no studies showing that conditioning can affect
sexual arousal in women. Since the O’Donohue and Plaud review was published, two
well-controlled studies using non-clinical samples have shown convincing evidence for
respondent conditioning of male sexual arousal. Lalumière and Quinsey (1998) found
enhanced genital responding to slides of partially nude females after they had been paired
with sexually explicit videotapes of heterosexual interactions, and Plaud and Martini
(1999) found increases in penile circumference to a penny jar after it was paired with slides
of nude or partially nude females. Letourneau and O’Donohue (1997) examined the role of
classical conditioning in women’s sexual responses but they failed to show conditioned
genital or subjective responses to a CS (an amber light) that had been repeatedly paired
with an erotic film. In contrast, Hoffmann, Janssen, & Turner (2003) found conditioned
genital arousal in women. Procedural differences may account for the discrepancy. Like
Letourneau and O’ Donohue, we used a visual stimulus as the CS and erotic film clips as
USs, yet our stimulus and interval parameters were more succinct (paralleling those used in
studies finding conditioned genital arousal in men) and our USs were more effective in
inducing genital arousal.
Our study was aimed at more than showing that women’s sexual arousal could be
influenced by conditioning. We used the same experimental paradigm to examine the
conditioning of genital arousal in both women and men. Photographs presented on
videotape served as CSs and erotic film clips that had been rated as arousing by both men
and women (Janssen, Carpenter, & Graham, 2003) served as the USs. Domjan and Hollis
(1988) proposed that males might show conditioned sexual arousal more readily, and to a
wider range of cues, than females. It has also been suggested that women’s sexual arousal
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may not be as readily conditionable as men’s (Bancroft, 1989; Kinsey, Pomeroy, Martin, &
Gebhard, 1953). However, Baumeister’s (2000) proposal that women are more erotically
plastic suggests that they could be more sensitive to conditioning than men. Potential
differences in propensity for sexual conditioning may involve gender differences in the
effectiveness of various CSs and USs in the conditioning of arousal. In addition to
examining gender differences in conditionabilty, we also explored the notion of biological
preparedness (e.g., Dellarosa Cummins & Cummins, 1999; Mineka & Öhman, 2002;
Seligman, 1970) in sexual conditioning, proposing that a sexually relevant CS (photograph
of an abdomen of the opposite sex) would be more effective than a sexually irrelevant CS
(photograph of a gun). Finally, assuming that subjects would be less likely to alter their
expression of arousal if they did not realize they were being conditioned, we also varied the
subjects’ awareness of CS presentation and in doing so their awareness of the CS-US
contingency. CSs were presented either “subliminally” (i.e., for 30 m/sec followed
immediately and hence backward masked by the film US) or “consciously” ( i.e., for 10
sec).
When stimuli were presented outside the subjects’ awareness, both women and men
showed conditioned genital arousal to the abdomen CS but not to the gun CS. These results
are similar to those found by Öhman, Esteves, and Soares, (1995) using a fear conditioning
paradigm, i.e., they found conditioned increases in skin conductance response to fear-
relevant but not fear irrelevant stimuli that were presented outside the subject awareness
and paired with a mild shock to the fingers. Even though our manipulation and
measurement of awareness were rather crude, our results suggest a prepared link between
sexually relevant stimuli and genital responses and support an independent role for
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automatic processing in sexual responding consistent with some models of sexual arousal
(Janssen, Everaerd, Spiering, & Janssen, 2000).
When consciously perceived CSs were used however, men again showed
conditioned increases in penile tumescence to the abdomen but not the gun CS, whereas
women showed the opposite effect, i.e., conditioning to the gun but not the abdomen
stimulus. The latter result was unexpected. Perhaps the gun-arousal associations in women
may have been facilitated by increased attention (Beylin & Shors, 1998; Shors & Matzel,
1997) or excitation transfer (Hoon, Wincze, & Hoon, 1977; Meston & Gorzalka, 1995;
1996; Meston & Heiman, 1998) as women (but not men) showed increased skin
conductance responses to the gun (but not the abdomen) CS. Small sample size in the
target group prevented appropriate assessment of this hypothesis, but we intend to examine
this issue in the future.
Our study hinted at gender differences in the conditions under which sexual
learning occurs, at least when consciously perceived CSs were employed. If fact, with both
subliminally and consciously presented CSs, conditioning appeared stronger in women than
men. However, the lack of a common physiological measure of arousal prevents a direct
gender comparison. Moreover, gender differences in arousal patterns during conditioning
could have accounted for the observed results. Men showed arousal responses to the CS
prior to and independent of conditioning, whereas women did not. Hence the observed
differences between women and men may have been due to differences in our ability to
detect learning rather than due to a genuine gender difference in the strength of the CR.
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In addition to replicating and expanding on the abovementioned findings, we have
begun to examine individual differences in conditionability, as well as to use CSs from
other sensory modalities.
Individual differences. There are most likely various individual differences in
classical conditionablity (e.g., Martin, 1997). Kvale, Psychol and Hugdahl (1994) found
that autonomic (cardiovascular) reactivity is positively correlated with the susceptibility to
learning a tone-noise association and to acquiring anticipatory nausea and/or vomiting in
people receiving chemotherapy. Kantorowitz (1978) showed a significant correlation
between extraversion and conditioning of pre-orgasmic sexual arousal and a significant
correlation between introversion and post-orgasmic sexual arousal. In our study we found
that conditionablity did not appear to be related to the amount of experience subjects had
with erotic film, however there was not much variation among our participants on this
measure. We also collected survey data from some of our subjects and correlated it with
the strength of the CR. Specifically, we measured introversion/extraversion and we
administered the Sexual Experience Scales (SES) subscale for Psychosexual Stimulation
(Frenken, 1981) and the Sexual Inhibition Scales/Sexual Excitation Scales (SIS/SES)
(Janssen, Vorst, Finn, & Bancroft, 2002). The former measures the extent that someone
seeks sexual stimuli of an auditory-visual or imaginary kind and the latter measures sexual
excitation (SE) or the propensity for sexual arousal and two forms of sexual inhibition
(SIS-1 and SIS-2). SIS-1 is inhibition related to performance failure and SIS-2 is inhibition
related to negative consequences. There were no clear relationships for men but for women
the strength of the CR was inversely related to their scores on both inhibition scales but the
correlations were not significant (p = .12, p = .13, respectively). This suggests that women
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who are low in sexual inhibition may be more likely to show conditioned sexual arousal.
However, what sexual inhibition means for women is unclear as the SIS/SES-female
version that was used was adapted from research with men.
Olfactory CSs. Olfactory cues play a large role in sexual arousal in animals, and
odors have been used as effective CSs in the conditioning of sexual arousal in a variety of
nonhuman species (Domjan & Holloway, 1998; Pfaus et al., 2001). While noxious odor
stimuli have been used as USs to decrease sexual arousal in clinical settings (e.g., Colson,
1972; Earls & Castonguay, 1989; Junginger, 1997), olfactory stimuli have not been used as
CSs in the conditioning of human sexual arousal. Studies indicate that smell plays a
significant role in human sexual attraction. Herz and Cahill (1997) found that odor is an
important guide for mate selection in women and men, and that women valued odor more
so than men. Herz and Inzlicht (2002) showed that, for women, body odor was more
important than looks (the reverse was true for men) and that, for women, smell was more
valuable than all but one social factor (i.e., pleasantness). Because people report that smell
is important in attraction and since the majority of fetishes are related to olfactory or tactile
stimuli (Money, 1988), humans, and in particular women, may be likely to associate sexual
arousal with odor cues. We are currently attempting classical conditioning of genital
arousal using an olfactory CS. Discrete presentations of an odor stimulus (delivered via an
olfactometer) were paired with erotic film clips as the US. A pilot study using only women
found evidence for conditioned arousal to a strawberry odor in three of six subjects. It
would be interesting to compare the relative effectiveness of an olfactory versus a visual
CS in women and men.
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The specifics of what is learned
Classical conditioning is typically interpreted as learning of a predictive
relationship in which the CS comes to signal the onset of the US, yet other types of
learning can result from exposure to Pavlovian procedures. For example, even though
conditioned taste aversion (CTA) learning is similar to other types of classically
conditioned avoidances, a flavor cue that has been paired with a nausea-inducing agent not
only comes to signal impending negative consequences but also itself becomes distasteful.
Taste cues that predict the onset of shock or other cutaneous phenomenon result in
avoidance but not acquired distaste (Pelchat, Grill, Rozin, & Jacobs, 1983; Pelchat &
Rozin, 1982). For example, if a person becomes ill after eating something, they may
become disgusted by the taste or smell of that food whereas if they experience an allergic
reaction (e.g., breaking out in hives) after consuming that food, it typically does not
become unpalatable. CTA learning appears to involve shifts in the hedonic value of the
CS. Perhaps this also occurs in some instances in the conditioning of sexual arousal. Rozin,
Wrzesniewski, and Byrnes (1998) proposed that the acquisition of fetishes may involve
aspects of what is known in the human conditioning literature as evaluative conditioning
(EC). Levey and Martin (1975) coined the term and described EC as an associative transfer
of valence as a result of exposure to Pavlovian procedures. A common paradigm used in
EC is pairing a picture of a “neutrally-rated” face (CS) with attractive or unattractive faces
(USs) which results in a positive or negative shift in the evaluation or “liking” of the CS as
assessed by verbal ratings. Most EC studies involve second order USs that are not
biologically relevant (e.g., a picture of an attractive face, an unpleasant taste), however EC
has been observed with a primary (shock) US (e.g., Hermans, Vansteenwegen, Crombez,
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Baeyens, & Eelen, 2002). Most human conditioned arousal studies assess learning by
changes in genital responding rather than by changes in self report. An exception is
Letourneau and O’Donohue (1997) who assessed but did not find a change in subjective
arousal ratings of the CS. However, this is not necessarily informative since their
procedures did not produce conditioned genital arousal. Further, when using primary USs,
a more indirect measure of EC (e.g., an affective priming task) is used to avoid demand
characteristics (for more details see De Houwer, Thomas & Baeyens, 2001). The erotic
photographs and films clips used as USs in conditioned arousal can be considered second
order USs but they produce a stronger behavioral response than those typically used in EC.
Hence it may be more appropriate to assess shifts in CS valence during sexual conditioning
using an indirect measure.
EC shares a number of properties with more conventional classical conditioning,
but it is more resistant to extinction, not as sensitive to changes in CS-US contingency or to
modulation (e.g., occasion setting) and can occur without awareness of the contingency (De
Houwer et al., 2001). Some research, mainly in nonhumans, suggests that the conditioning
of sexual arousal may show some characteristics of EC. In rats, Pfaus, Theberge, and
Kippen (2003) found that an initially aversive odor can become appetitive after copulation
with females scented with this odor, which suggests a hedonic shift in CS valence.
Villarreal and Domjan (1998) found that male gerbils showed conditioned approach to an
odor CS even though it was inconsistently paired with copulation, suggesting that learning
in this situation may not have been particularly sensitive to contingency. In humans, the
acquisition of a fetish appears to involve affective change. In laboratory studies, Langvin
and Martin (1975) found some evidence that the strength of conditioned arousal in men did