EFFECTS OF INFORMATION AND A PRIORI PROBABILITY OF PAINFUL STIMULI ON PAIN SENSITIVITY AS CONTRASTED IN CLASSICAL PSYCHOPHYSICS AND SIGNAL DETECTION THEORY

EILEEN MARIAN BRADY, Fordham University

Abstract

The present investigation was undertaken to evaluate two contradictory predictions of classical psychophysical theory (CPT) and signal detection theory (TSD). CPT predicted that practice would stabilize the absolute threshold (RL), while TSD hypothesized that practice would influence the subject's criterion (L(,x)), thus altering RL. Secondly, CPT postulated that variations in information regarding alterations in the a priori probability of painful stimulus occurrence would not influence pain reports of trained subjects. TSD predicted that variations in the a priori probability of painful stimuli would significantly effect the informed group's L(,x), thus altering RL without influencing sensory discriminability (unit-d').^ The study examined the effect of practice in stabilizing pain reports, assessed by RL, unit-d', and L(,x). Twenty college women rated each of six radiant heat stimuli; each intensity was presented 40 times during the session. Practice was terminated when none of the pain response measures exhibited significant differences for two consecutive sessions. An average of six sessions was required to stabilize all of the pain response measures. Analysis of individual data indicated that no systematic intrasessional pattern of variation emerged for any of the pain response measures. These results provided partial support for both theories.^ These trained subjects completed two experimental sessions which were designed to examine variations in pain reports as a function of the extent of information regarding the a priori probability of painful stimuli. Ten subjects received information about the three a priori probability conditions which were 25%, 50%, and 75%, while ten subjects remained uninformed. At least 20 trials of each of the less frequently occurring intensitites were rated by the subject.^ The analysis of variance (ANOVA) results indicated that the informed group's RL significantly decreased as the a priori probability increased, while the uninformed group's RL remained relatively stable. Variations in either a priori probability or the extent of information did not significantly effect unit-d. The ANOVA results established that informed group adopted significantly more liberal L(,x) as a function of increments in a priori probability. The uninformed group's L(,x) remained relatively stable. These results supported TSD predictions, demonstrating that pain reports are concomitantly influenced by sensory discriminability and cognitive factors.^

Subject Area

Experimental psychology

Recommended Citation

BRADY, EILEEN MARIAN, "EFFECTS OF INFORMATION AND A PRIORI PROBABILITY OF PAINFUL STIMULI ON PAIN SENSITIVITY AS CONTRASTED IN CLASSICAL PSYCHOPHYSICS AND SIGNAL DETECTION THEORY" (1983). ETD Collection for Fordham University. AAI8326684.
https://fordham.bepress.com/dissertations/AAI8326684

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