APE: Adaptive probit estimation of psychometric functions

Abstract

We developed a scale to measure internalized homophobia in men who have sex with men, which is comprised of items derived from theoretical and clinical reports of internalized homophobia. Two hundred two men who have sex with men and who attend "Man to Man" sexual health seminars in a midwestern U.S. city completed the scale at baseline. Orthogonal factor analysis revealed four dimensions of internalized homophobia: public identification as gay, perception of stigma associated with being homosexual, social comfort with gay men, and the moral and religious acceptability of being gay. Factor scoring of these dimensions indicated that they were associated significantly with relationship satisfaction, duration of longest relationship, extent of attraction to men and women, proportion of social time with gay people, membership of gay/bisexual groups, HIV serostatus, and disclosure of sexual orientation. Internalized homophobia is measurable and consists of four dimensions that are associated significantly with low disclosure, shorter length of and satisfaction with relationships, lower degree of sexual attraction to men and higher degree of attraction to women, and lower social time with gay people.Internalized homophobia is a central construct in the symptomatology and treatment of gay men and lesbians. Cabaj (1988) argues that it is the main dynamic in neurosis in homosexual people, with ego-dystonic homosexuality, previously a diagnostic category, being described as dissatisfaction with being homosexual and as being associated with low self-esteem and self-hatred. Thus, the diagnostic category of ego-dystonic homosexuality included what currently is described as internalized homophobia. Cabaj suggests that internalized homophobia will affect symptomatology, transference, and countertransference in psychotherapy with homosexual people. In addition, Kahn (1991) has noted that theories of homosexual identity formation are based on the assumption thatThe "Man to Man" seminars were funded by a grant from the AIDS/STDs Program of the Minnesota Correspondence should be addressed to Dr.

Adaptive psychophysical procedures

“…the dB scale. Estimation of threshold and slope Hall (1981) and Watt and Andrews (1981) proposed two different methods, both of which estimate two parameters: the threshold and the slope of the psychometric function. Except for the idea of splitting the complete session into several blocks, and of estimating the psychometric function's parameters between these blocks of presentations, both use different methods for parameter estimation and stimulus placement.…”

On the scaling of size judgements by orientational cues

“…The actual size of the stimulus on each trial was determined by Watt and Andrews' (1981) method of adaptive probit estimation (APE). On each trial APE chooses the actual stimulus value randomly from four possible values placed symmetrically around the mean (standard) stimulus value.…”

Estimating everyday portion size using a ‘method of constant stimuli’: In a student sample, portion size is predicted by gender, dietary behaviour, and hunger, but not BMI

“…Much of the psychophysical function comprises responses that are trivial because the participant consistently chooses either 'too much' or 'too little' (for example, see extreme end points of the function in Figure 1). To greatly improve the efficiency of our procedure we chose to use the Adaptive Probit Estimation algorithm (Watt & Andrews, 1981). With this approach, only a subset of the comparison range is tested.…”