The study of ejaculatory response in men in the psychophysiological laboratory

Journal of Sex Research, Spring, 1997 by David L. Rowland, Stewart E. Cooper, A. Koos Slob, Elisabeth J. Houtsmuler

Sexual psychophysiological researchers have had limited success in studying ejaculatory response in the laboratory in men and, more specifically, in identifying factors that differentiate the sexual response of men with premature ejaculation (PE) from controls. A number of methodological limitations may have contributed to the lack of effects in these studies, including lack of stimuli and response measures specific to ejaculatory response. To understand further the sexual response patterns of men with premature ejaculation, penile response, subjective arousal, and subjective and objective measures of pending or actual ejaculation were measured in men with premature ejaculation and controls to two types of stimulation: an erotic video and an erotic video plus penile vibrotactile stimulation. Erectile response differed across stimulus conditions, but not across groups (men with PE versus controls). A number of group, stimulus, and group by stimulus effects were found on subjective measures of arousal, perceived penile response, and ejaculatory response. In fact, 5 of 14 men with PE ejaculated under the combined stimuli, whereas only 1 of 8 controls ejaculated. These findings support the efficacy of using penile tactile stimulation and assessment of objective and subjective correlates in laboratory-based investigations of ejaculatory response.

Psychophysiological researchers investigating sexual dysfunction been successful in differentiating response of men with erectile dysfunction (ED) from sexually functional men (Bancroft et al., 1985; Beck & Bar1986; Rowland & Heiman, 1991). der laboratory conditions where participants are presented with erotic stimuli and their sexual response is measured, clear differences between and functional men in both genital response and subjective arousal seen. In contrast, such experimental studies have been relatively unsuccessful in differentiating the sexual response of men with premature ejaculation (PE) from that of functional counterparts, in that the response patterns of these groups are indistinguishable (e.g., Kockott, Feil, Ferstl, Aldenhoff, & Besinger, 1980; Spiess, Geer, & O'Donohue, 1984; Strassberg, Kelly, Carroll, & Kircher, 1987). Failure to elicit different response patterns between PE and control men in the oratory has prevented a systematic, controlled study of premature ejaculation, a disorder that is currently not well understood (Grenier & Byers, 1995; Ruff & St. Lawrence, 1985).

The lack of differences between PE and control groups in previous studies may be attributed to inadequate stimuli and/or response measures. Specifically, researchers have generally relied on visual erotica as the mode of sexual stimulation, yet men with PE typically ejaculate rapidly when tactile stimulation to the penis is involved. Furthermore, previous researchers have focused mainly on erectile measures and paid little or no attention to objective or subjective measures of ejaculatory response (e.g., actual ejaculation or feelings of impending ejaculation), yet such measures are clearly critical to the study of premature ejaculation. Finally, most laboratory studies have been unable to demonstrate genital response differences between PE men and controls when relying on penile circumferential measures. Yet differences in penile rigidity may be the more relevant measure for assessing genital response under high levels of arousal, as might occur in men with PE (e.g., Rowland & Slob, 1992).

The purpose of the current study was to identify conditions that enable successful study of ejaculatory response in the psychophysiological laboratory. To address the shortcomings of previous studies, our procedure involved stimuli and response measures more specific to PE. We chose sexual stimulation that included a tactile component (administered to the penis) as well as a strong visual component. Response measures were not limited to penile circumference and subjective arousal but included a measure partly responsive to penile rigidity and, more importantly, subjective and objective assessments of pending or actual ejaculatory response. Using these parameters, we examined whether the addition of penile vibrotactile stimulation to the sexual situation might affect measures related to erectile and ejaculatory response and whether men with PE might show stronger sexual response (subjective, erectile, and ejaculatory) to vibrotactile stimulation than their functional counterparts.

Method

Participants

Twenty-two Dutch men participated. All were heterosexual, at least 18 years old, and had obtained the consent of their sexual partner. These participants were compensated with $15 or with the cost of travel expenses to and from the laboratory. Eight men were sexually functional volunteers (control group), and 14 were patients with premature ejaculation (PE group). Men in the PE group were referred by the urology clinic of a major academic hospital where they had sought help for a sexual problem. Specifically, these men had been initially diagnosed on the basis of self-reported inability to control ejaculation during coitus with accompanying subjective or interpersonal distress; each reported having had the dysfunction for a minimum of six months. Consistent with this classification, these men reported ejaculation latencies of one minute or less and indicated significantly fewer thrusts to ejaculation than controls (see Table 1). Six men in the PE group reported secondary erectile problems, as defined by the inability to achieve or maintain erection sufficient for coitus or masturbation at least "some of the time" (i.e., based upon clinical interview and supported by scores ranging from 3 or higher on a 7-point scale where 1 = never to 7 = always, on a questionnaire item assessing this aspect of sexual function). These diagnoses were further confirmed through an extensive medical history and a structured clinical exploration of a 50-item sexual response inventory based on multi-axial dimensions (Schover, Friedman, Weiler, Heiman, & LoPiccolo, 1982) conforming to the DSM-IV diagnostic categories of desire, arousal, and orgasm (American Psychiatric Association, 1994). Before participation in the study, all patients underwent a complete physical examination during which physicians paid special attention to urogenital, neurological, and vascular function to ascertain that these men had no history of disease, surgical procedures, or medication use known to affect sexual functioning.