Successive luminance difference thresholds and brightness as a function of the interstimulus interval and durations of successive flashes

Monocular,successive luminance difference thresholds (ΔI) and brightness matches (PSE) were obtained by the method of constant stimuli for two flashes successively presented to the same retinal area. Variations in interstimulus interval first-flash duration,and second-flash duration were the independent variables investigated. ΔI decreased as a function of ISI,while PSE remained relatively uninfluenced. An intensity-duration reciprocity was observed with increases in either first- or second-flash duration. Equal increases in duration of both flashes led to a constant value of ΔI. A Broca-Sulzer effect was also noted. In another study, a 10-msec, variable-luminance Standard was followed after 500 msec by either a 10-msec or a 320-msec test flash that was compared to the Standard. The results indicated that the rate of change of brightness with changes in luminance of the Standard was faster for the 10-msec flash than for the 320-msec flash. The rate-of-change hypothesis would predict that the 10-msec flash should have the smaller ΔI. The results for two Ss indicated the opposite: AI was smaller for 320-msec than for 10-msec flashes. A modification of the hypothesis was suggested such that it may be the energy increment (Δlt) required for detection that is related to the rate at which brightness changes with energy.     

Diagnostic judgments as a function of client and therapist race

The purpose of the present investigation was to examine the process of differential evaluation of clients as a function of client and therapist race. It was hypothesized that race of client and therapist would interact, influencing the judgments of client psychopathology, appropriateness for therapy, verbal facility, and likelihood of treatment success despite standardization of the clinical stimuli. Graduate students in clinical psychology and with varying levels of training (i.e., 1 to 5 years) were asked to rate videotaped interviews of clients in which race of the client and level of psychopathology (i.e., normal, neurotic, and psychotic) were systematically varied. There were significant differences in ratings as a function of race of client, race of therapist, and level of psychopathology observed. Black clients were not rated differently on degree of psychopathology but were rated as less verbally skilled and less appropriate for treatment but more likely to benefit from treatment than white clients. Contrary to expectations, white therapists tended to underrate the pathology of black clients. On the other hand, black therapists tended to overrate the pathology of white clients and made mixed judgments of black clients. The implications of these findings are discussed.This study was supported in part by NIMH Research Centers in Minority Institutions (RCMI) Grant G12RR03206-2.     

Achromatic color matching as a function of apparent target orientation,target and background luminance,and lightness or brightness instructions

In two experiments, achromatic color matches for a fixed target, under constant illumination, were compared under conditions where the target appeared perpendicular to illumination direction and coplanar with the background (monocular viewing) and where the target appeared nonperpendicular to illumination direction and noncoplanar with the background (binocular viewing). Contrary to the coplanar ratio hypothesis, which predicts a “lightening” of the target seen coplanar with a darker background, a general “darkening” of the target occurred for both white (N9.5/) and black (N3/) backgrounds and for both dark (N5.5/) and light (N6.5/) targets. This darkening effect was greatest for the darker target and black background, and approximately equal for other combinations of target value and background. The direction of the darkening effect is consistent with the albedo hypothesis, which assumes an inferential correction for changes in conditions of illumination. However, variation in the magnitude of the darkening effect is problematical, and cannot be easily explained by any existing theory. In both experiments, instructions to judge “lightness” or “brightness” failed to produce any substantial differences in performance, although postexperimental questioning suggested that subjects had a verbal understanding of these concepts. Apparently, under reduction conditions, subjects lack cues to illumination and make only lightness matches, regardless of instructions.     

Apparent brightness of a rotating arc-line as a function of speed of rotation

52 Ss were required to adjust the brightness of a center fixation line to equal that of the apparent brightness of an arc line viewed at a distance from the fixation point subtending an angle of 12° to the eye. Adjustments were made when the arc-line was stationary and rotating at speeds of 30, 45, 60 and 75 rpm. It was found that brightness enhancement occurred with increase in speed. This result was interpreted as supporting Ansbacher's account of distortion in the perception of moving arc-lines.     

Emotion judgments do not differ as a function of perceived nationality

This article reports three studies concerning the relationship between emotion judgments and perceived nationality of the expressors being judged. Study 1 demonstrated that observers do not reliably make implicit assumptions about the nationalities of the expressors in judgment tasks. Study 2 examined judgments of Americans and Japanese observers who were told that Caucasian and Asian expressors were Americans and Japanese, respectively, and who made fixed‐choice judgments and intensity ratings. Study 3 examined judgments of Americans given similar instructions and who used a multiscalar rating task. Neither Studies 2 nor 3 provided evidence that nationality information affected judgments. These findings have implications not only for basic emotion theory, but also for international and intercultural communication training.     

Lifted-weight difference thresholds as a function of hand

A study was conducted to determine if the two hands of right-handers are differentially sensitive to changes in perceived weight. Using the method of limits, the left and right hands of 20 college students were tested at each of three reference weights: 90, 100, and 110 gm. Results indicated that, over-all, difference thresholds for the two hands were not reliably different, though a trend did emerge toward greater right-handed sensitivity to weight changes at smaller weights and greater left-handed sensitivity at greater weights.