A Psychophysiological Investigation of Sexual Responding in Heterosexual Males and Females

A Psychophysi ological Investigation of Sexual Responding in Heterosexual Males and Females This stud y evaluates and compares the subjective and physiological arousal responses of heterosexual males and heterosexual females. Although several researchers have studied the patterns of sexual respondin g in reaction to erotic stimulation for males and/or females (Wincze, Hoon & Hoon, 1977; Heiman, 1977 ; and Sanford, 1974), to date there has been no systematic attempt to compare the patterns of sexual responding for these two groups using comparable measuring devices. With the recent development of more sensitive measuring devices, it is now possible to research this area. The goals of this study were several; (1) to evaluate and compare males' and females 1 differential patterns of physiological responsivity to a variety of erotic stimuli, (2) to evaluate and compare differential patterns of subjective responsivity for males and females, (3) to examine the relationship between measures of the physiological arousal response and the reported subjective arousal for males and females, and (4) to determine the extent to which a surface photoplythesmograph transducer was capable of dlscriminating sexual arousal from nonarousal states for males. Methodologically , a group comparison paradigm was employed. Eight males and eight females were shown a var:!_ety of erotic and nonerotic films. The films were sequentially presented then withdrawn. During

been no systematic attempt to compare the patterns of sexual responding for these two groups using comparable measuring devices.
With the recent development of more sensitive measuring devices, it is now possible to research this area.
The goals of this study were several; (1) to evaluate and compare males' and females 1 differential patterns of physiological responsivity to a variety of erotic stimuli, (2) to evaluate and compare differential patterns of subjective responsivity for males and females,   Tables   Table l   Table 2   Table 3   Table 4   Table 5   Table 6   Table 7   Table 8   Table 9 Cell Means and Standard Devia tions for the ila le Penile Circumference Data A.NOVA Summ 3. r y  Introduction V ii thi n the l ast decade, ·,cient ists ha ve begu;1 to systematic ally stud y sexuai behavior and sexual arousal patterns. As a result of the earl y work of Masters and Johnson ( 1966) , the avenues of exploration in the area of sexual behavior and arousal were opened. Although Masters an d Johnson's studies provided only descriptive data of sexual behavior, their pioneering work ser ved to lift the social taboos against the laborator y stud y of sexual responding.
As Zuckerman ( 1971) points out in an early re view, the most valid measure of sexual responding is a direct genital measure.
With the development of objective measures of genital arousal for both males (Freund, 1957;Barlow, Becker, Leitenberg & Agras, 1970) and females (Geer, Morokoff & Greenwood, 1974) Although a fair amount of work has been done studying the arousal patterns of normal, deviant, and dysfunctional individuals, to date it has been impossible to make direct comparisons of the male and the female s exual r esp ons e . Typ ic21l y, chang es in vagi na l va socon gesti on have been us ed to indicat e th e presenc e of fema le sexual arousal and penile circumference change has been used as an indice of male sexual ar ous a l.
In t he r ev ie w which follows, studies wi l l be pres en t ed by population.
Since questions regarding the parameters of the sexual response ha v e, in most cas es, be en addressed wit hi n t he context of a study evaluating patte rns of sexual responding fo r a given population, th e di scuss i on of these issues will be i nclud ed indi vi dually for each population. A summary of the research findings wi l 1 follow the re v iew.

Heterosexual and Homosexual Males
Several studies have assessed the arousal patterns of heterosexu a l males. Sanford (1974) reports that for 6 males, viewing films depicting a heterosexual couple activ ely engaging in intercourse produced a significantl y greater increase in ob jective measures of sexual arousal than vie wing films of nudit y . It wa s also found that films elicited greater changes in measures of arousal than did slides depictin g the same content. This finding was replicated by Mcconaghy (1974). In a comparison of 6 male heterosexuals to 6 male homosexuals, M avissakalian, Blanchard, Abel and Barlow (1975)  In an assessment of male and female differences in subjective ratings of erotic stimuli, Steele and Walker (1974) found significant differences between the two groups. Males tended to r3.te slides which were consi de red t o be more ext r eme (e . g ., sedomaso chi srn, homosexu al cunn il in gus, heteros exual fe ll2. t io ) hi gher t han femal es , who seemed to pr efe r more moderate slides (e .g. , nude ma les with exposed genitalia).
Although both males and females reported minimal sexual stimulation and minimal Ji kin g for the slides , the male's ratin gs were higher on both scales. The authors suggest that 1 'males are more responsive to visual erotic stimuli than are females' 1 (p . 463).
Heiman (1978) compared the sub jecti ve and objective arousal patterns in males and females and found th at for both groups the amount of previous sexual experience had no effect upon measures of sexual arousal to erotic films. with the transsexual group showing more homosexual arousal than the homose xua l gr oup. Bot h he t eros exua l and t.r aTi s se xua l ma l es had a decre a se in t he peni l e aro us al re spon s t to the nonpreferred s ex , mal e and f ema l e respectivel y . It was a l so found tha t t he tr ans se xua ls had a larger GSR to fe mal e stimuli tha n did the homos exuals . Thes e authors sug gest th at t he male transsexu a l , (who beli eve s he i s in fa ct a female) i s s exuall y intereste d in men and tends to orient to ward femal e s as a function of h is inte r est in acqui r in g a female body . When comparing the self-re port of sexual intere s t t o an obj ecti v e measur e of se xual arousal in a gr oup of 24 male transsexuals, Barr , Raphae l and Hennessey (1974 )  For t he purp os es of t he pro pos ed s tud :: ' , 1:.he above mentioned finding s ar e extremel y import ant. The ab ili t y t o det ec t chan ges in va scularizati on of sur fa ce pen i1 e t is sue associated with the prese nc e or absence of erotic stimuli pro vid es the researcher or clinician wit h a measure of mal e sexLlal arou sal whic h is more di rect ly compar ab ie to measures of female arousal, making comparisons bet ween these groups possible . It is possible that the surface photopl yth esmograph would provide measures of the onset, offset , and magnitude of the sexual response in males which would be equivalent in character to the arousal res ponse measured in females .
The followin g stud y is an attempt to investigate and compare the physiological and co gnitive arousal patterns of normal heterosexual males and normal heterosexual females . By working within a controlled research paradigm, patterns of sexual responding within each group may be suggested and between group comparisons can be made. In response to Barlow's (1977 ) suggestion, that sexual responding may be considered to occupy 3 response domains (verbal, beha vioral and physiological ) , selfreport, behavioral and physiological measures are used.

Subjects _Group 1
One group of Ss were normal heterosexual female volunteers (n = 8) .
Ss were graduate and undergraduate students from the Universit y of Rhode . Onl y those recei v ing a score of 11 0 11 , i ndi cati ng exc lu s iv e heter os exua l s exua l or ie ntat i on, were inc l uded in t he stud y .

Group 2
A secon d gro up of Ss inc l ude d normal he t eros exual ma le vol unteers (n = 8) . M al e Ss wer e solic i ted fr om t he same population s as the fe ma l e Ss. Again, onl y t ho se Ss who received a score of "0" on the Kinse y Scal e were included in t he stud y .
To insur e th e l ac k of any ps ychi atri c disturbanc e, al l Ss in eac h group under went an i nt er v ie w pre cedi ng the experimental session . A qualified member of the research t eam administered the intervie ws.
A potential S i n either grou p who reported an aversion to explicit sexual material was not include d in the study. All Ss were paid ten dollars for their particip ation .

Measures
Behavioral measures of sex -role typical beha vior, self -report measures of sexual beha v ior and s exual arousal, and physiological measures of ar ousal were ta ken.

Behav ioral ~leasures of Sex-Role Behavior
Sex roles may be viewed as multidimensional const r ucts. Genderspe c i fic motor beha vior re presents one dimension of this construct. The Barlo w et al . ( 1973) M as culinit y/ Ferninit y Behavioral Rating Scale is designed to di scriminate sex -role stereotypic sitting , standin g and wa lking beha vior s . This instrumen t was emp lo yed. to ascertain the extent t c which ea ch S emitted character i stic se x-ro l e motor beha v i ors . This measur e was ta ken surre pticio us l y t y a rat. er trained in it's use. The rater was seated i n th e rece ptLrn are a out.si d2 of the expe rimental room.
Each S was asked to wai t in the r ec ept ion area for thre e minutes prior to being brought into the experimental room. Durin g the three minutes , th e rater comp leted t he ~lasculinit y/ Feminit y Beha vioral Rating Scale.

Subjecti ve Measures
The following subjective assessment procedures were used. which is proportional to the location of the lever in it's range.
This voltage differential drives a Grass 7-DAE Driver Amplifier so that millimeters of pen deflection correspond in a linear manner to the position of the lever in it's range.
5. Attitudinal ratings of "pleasantness" were collected using a 7-point Likert scale following each stimulus presentation. This procedure is described by Mavissakalian et al . (1975 ) .
6. Subjective ratings of "percent of sexual arousal" experienced were collected following e&ch stimulus presentation. Each S was asked to report on a scale from Oto 100 the amount of sexual arousal he/she experienced during the preceding film . Hence, the greater the vasocongestion, the less reflectance, which when recorded is translated into increased arousal. Insertion of the probe elicits no more arousal than insertion of a tampon, therefore, does not confoun~ the physiological recordin gs of arousal .

Measures of ArousQl
The use of the probe as a reliable and valid measure of sexual arousal has been demonstrated in se veral studies of normal and dysfunctional females (W incze et al., 1976;Wincze et al . , 1977 ;Heiman, 1975) .
The fe male Ss wer e in str uct ed t o ins er t t he probe in priv ate .
Placement of t he pr obe was mani p1. 1~c1 t ed un~-:.1 2 c lea r s i gnal was received.
The connectin g wire was secured to th e S ' s rig ht thi gh. This helps to e limin ate movement artifact . A fe male i nv esti gator ch ecked to insure tha t the probe had be en inserted and secured correctl y . Throughout the exp erimental session the S was seated in a comfort able reclinin g chair.

Anal ys i s fo r Males
Results of t he 6 x 5 ANOVA in di cat e si gni ficant main effects for t he s ti mu l us conditio n (F (7 , 35) = 11. 93, p < . 001), for tim e (F (7 , 28) = 9 .53, p < . 001) and for th e intera ct i on of cond i t i on by ti me (F(7 ,14 0) = 2 .1 0, p < . 01) for the ma le penile circu mferenc e da t a .  A 6 x 5 ANOV A for the male penile vasocongestion data was performed. A 6 x 5 ANOVA for the female subj ective arousal data was performed.

In s er t Tables 14 & 15 About Here
In order to int erpret the inte ra ctio n , Simple Effects tests were pe rformed for cond i tions at each of the five levels of time.
Results of these tests sho w significant (p < .Ol j effects for condi t ion at Times 2, 3,4 and 5. Newrnan-Keuls tests f or condition at these times were performed to determine th e source of the significant differences. These data are presented in Table 16. Insert

Ar1other interest i ng point f or comparison between mal es and females
1s the effect of time on phys i olo gical arous a l. Although significant differences in both the males' and females' levels of physiological arousal while viewing the various erotic film sequences were obser ved, when looking at the time course of physiological sexual arousal, it was found that the males became increasingl y aroused over time while viewing the erotic films, but, the females' sexual arousal did not increase over time.
This suggests that the females reached and maintained their maximum level of physiological arousal for a par t icular film earl y in the presentation of that film sequence, whereas the males displayed a more gradual increase in physiological arousal throughout the presentation of a particular film sequence. There are two potential explanations for these findings. On the one hand, there may in fact be differences between males and females in the expression of physiological arousal over time, or, the differences found in this investigation may be a function of the different measures used to determine the presence of physiological arousal in males and females. Finally, Hoon and Hoon (1977) suggest that males may simply find erotic visual stimulation to be more arousing than do females .
The previous discussion has focused primarily upon the subjects as the source of differences in levels of sexual arousal achieved in the presence of the erotic stimuli. The characteristics of the erotic films also need to be considered . The film sequences used in this study were not matched for aesthet i c quality, that is, the actors and actresses varied between the films and some of the films were in color and some in -38black and whit e . The proble m of tr ying to match stimulus f ilms exists for all research ers in this ar ea, and may acco i.mt for some of the disparate findings in t he literature. Anothe r poin t to be considered is t he overall er otici sm of the stimulu s fil ms for males versus females.
Since pronography is produced primarily by and for males, it is likely to have less erotic val ue for females. Each of t he se variables may possibly be contrib uti ng to some of the di f fe r ences obser ved in this stud y .

Differential
Patterns of Subjective Respondin g to Erotica: The findings of this stud y are consistent with those of other researchers who have suggested that males and females differ in their subjective responsiv eness to sexual stimulation (Steele & Walker, 1974;Heiman, 1975;and Izard & Caplan, 1974) . The focus of these studies has been upon differences between males and females in lev e ls of responsiveness to sexual stimulation. In summary, their findings suggest that males re port more subjectiv e arousal to sexual stimuli than do their female counterparts. The next important step is to begin to look at the differential le vels of reported se xual arousal in reaction to sti muli re presenting a variety of sexual beha viors. This information would provide a description of patterns of subjective sexual responsivit y characteristic of males and females.
Results of this stud y suggest that groups of males and females emit differential patterns of subjective sexual res ponding. The ma les reported significantl y high levels of subjective sexual arousal in the presence of the gro up sex, lesbian and he terosexual film sequences (in that or der ) . The females re porte d sig n ificantl y high levels of subjective arousal during the hete r osexual, lesbian and group s ex films .
Nei th er the males nor t he females reported any subjective arousal durin g the homosexual film sequence.

Relationship
Bet ween Objective and Subjec t iv e Measures:  (1975) and Heiman (1977) found significantl y high relationshi ps between these two measures of male sexual arousal. Overall, the literature appears to su gg est that for most males th e re is a r e lativ e l y high relationship between objective and subjective measures of s exual arousal, but that this relationshi p is far more variable ac r oss females. The results of the present investigation support these findi ng .
There are several possible explanations for the lack of relationship bet ween objective and subjective measures for some females.
Bancroft (1971) suggests that males may be using the degree of erectness of the penis when reporting their subjective arousal.
Whereas males can use this as an overt feedback mechanism when estimating their subjective arousal, females must rely upon much more subtle physiological cues.
During the debriefing which followed the experimental session in the current investigation, each subject was asked what information he or she was using to estimate subjective arousal. A11 of the females and 7 of the 8 males reported using both changes in their genetalia and cognitive changes to estimate their arousal.
Since the male genital changes are far more apparent than the subtle changes which occur for females, it may be that the males had more information upon which to base their estimates. Also, it is possible that it was more difficult for the females to discriminate changes in low levels of sexual arousal than it was for the males to discriminate changes which were occurring at higher arousal le vels.
It is interesting to note that for some of the females there was a marked discrepancy between their objective and subjective measures of arousal while viewing the gr oup sex film. Although the physiological data indicate that the females acquired the highest levels of sexual arousal while viewing the group sex film, the females rated the heterosexual and lesbian films as be in g more subj ectivel y arousing . It is possible that the fe males t ended t o rate their arousal in compliance with what the y assumed societ y would sanctio n . These results replicat e thos e presented by Wi ncze et al . (1977) .

Subjec ts:
Since th e majorit y of studies of sexual behavior rel y on a relativel y small number of volunteer subjects , it is important to describe the demographic characteristics of the popu lation. For example, potential sub jec t differences across studies may accoun t for some of the differences in relationship s reported in the literature between objective and subj ective measures of sexual arousal. The individuals who volunteered to participate in this stud y were all either undergraduate students or college graduates.
Although there was an attempt to get volunteers who represented a range of age groups, the actual range was from 19 to 28 yea rs, with a mean age of 22 years. It is also important to note that the subjects in this particular stud y expressed more androgenous sex-role attitudes and had more sexual experience than one would assume is representative of the population at large. It is quite possible that these variables could effect both objecti ve and subjective measures of sexual arousal. Also, the fact that these people volunteered to participate in a study of sexual behavior may make them a unique group in the population.
It is possible that since all of the sub j ects in this stud y were involved in academics that the y were more in tune with changing social mores and perhaps more likel y t o admit being sexuall y aroused to a variet y of films than one woul d expect to find in a cross section of th e population. Techn olo gi ca l advances should also be ta ken advan t age of for the stud y of sexu al beh avi or. For ~xan~le, th e us e of u l tr as ound presents a ver y interestin g possibi l it y for fu tur e examin ation of the human se xual response. An extre mel y s ens iti ve ultras oni c dev ice de si gned to detect chan ges in bl ood flow, call ed t he dopp ler, has been use d in medic i ne for approximatel y 10 years, but has never been used to assess se xua l arousal.                 This is a linear scale. Therefore, 2 is twice as much as 1 , 10 twice as much as 5. Please move t he lever as close to this number or degree of sexual arousal as you can.
(The subject will then be given practice trials wi th feedback. He/She will continue pr acticin g until there is no more than 5% error.) Try to remember to use the le ver continuousl y even when there are only small changes in how sexuall y aroused you think you are. Also use the lever continuousl y during brea ks between the film. Keep your hand on the lever at all times.
You may base your devision on how sexuall y aroused you feel on as many or few cues, or signs, as you like. These cues may include your bodily response (feeling of warmth, tinglying, heart beat, etc.) or your thoughts or feelings about the scene.
One final note, there are nc, right or wrong ways to react to these scenes. Each person is unique. Also, your charts will be coded and kept confidential. Group Sex Film -a color film depicting two males and two females engaging in heterosexual behaviors including intercourse and oral sex.
The characters in all of the films were nude throughout the film sequences.
There was a musical soundtrack for each of the films.