利用反诱导消除McCollough效应

ＭｃＣｏｌｌｏｕｇｈ效应在完全黑暗和自然视觉条件下的消退过程很缓慢,而利用同频补色条栅来进行反诱导,能在十几分钟内消除显色效应。消除所用时间与反诱导条栅的亮度、颜色和栅条间距（空间频率）有关。进一步说明导致ＭｃＣｏｌｌｏｕｇｈ效应恢复平衡的主要因素跟网膜刺激方式有关。     

Duration comparison: relative stimulus differences stimulus age, and stimulus predictiveness.

Under a psychophysical trials procedure, pigeons were presented with a red light of one duration followed by a green light of a second duration. Eight geometrically spaced base durations were paired with one of four shorter and four longer durations as the alternate member of a duration pair, with different pairs randomly intermixed. One choice was reinforced if red had lasted longer than green, and a second choice was reinforced if green had lasted longer. Performance was compared when all the base durations and their pair members were included (entire-range condition) or when only the four longest base durations and their comparison durations (restricted-range condition) were used. Discrimination sensitivity decreased for longer duration pairs under both conditions, supporting a memory-based account. Sensitivity was lower under the restricted-range condition. Under both conditions, a bias to report "green as longer" increased as the second green duration increased. Bias changed as a matching function of the green-duration predictiveness of the correct choice. The results are related to a quantitative model of timing and remembering proposed by Staddon.     

An empirical look at the Defence Mechanism Test (DMT) Stimulus effects

Based on a sample of non-clinical subjects (N=74) the study examines the Defence Mechanism Test (DMT) by focusing on when perceptual distortions, called ‘signs of defence’ in DMT terminology, occur (distribution in exposure duration), which part of the picture is involved (distribution in localisation), and which ‘signs’ go together (using correlation and factor analyses). The results disclosed that the occurrence of perceptual distortions (‘signs of defence’) was related to exposure duration (some ‘defences’ are more frequent at brief exposures, some others at longer exposure durations), and to localisation on the picture. The location of misperceptions to the central person (hero) or the peripheral person (pp) of the picture was the major explanatory principle for the distribution of ‘signs’ on factors. Rather than capturing psychodynamic defence mechanisms, which is the theoretical basis of the test, the analyses imply that the DMT seems to measure misperceptions which are a function of the localisation of persons on the stimulus picture and of exposure durations.     

Depression,self-focus,and social interaction

The accuracy of depressed and nondepressed subjects' perceptions of their own and a social interactional partner's performance was investigated. Twenty depressed and twenty nondepressed college students participated in dyadic interactions and then rated their own and their partner's social behavior. The interactions were also rated by objective coders. Depressed subjects were differentiated from nondepressed subjects on several measures by both the coders and the subjects. Depressed subjects' self-ratings were correlated with the coders' ratings more often than were the nondepressives' ratings, suggesting depressives provided more accurate self-observations. Contrary to prediction, depressives were also more accurate in judging their partner's behavior. Depressives experienced heightened levels of self-focused attention, but this attentional focus did not mediate the relationship between depression level and self-accuracy. Finally, an analysis of the verbal statements suggests that performance differences between depressives and nondepressives may be a function of the quantity, rather than the quality, of the verbal production.     

Cognitive components in risk perception: Natural versus manmade risks

In a questionnaire study 106 Norwegian students rated natural and manmade hazards according to risk magnitude and public versus private responsibility for risk management. Another group of 50 subjects judged 36 natural hazards on nine risk dimensions used in previous psychometric studies of ‘manmade risks’. When ratings on nine risk characteristics for natural hazards were factor analyzed a three-dimensional solution was found, with one active/passive dimension, one potency dimension, and one novelty dimension. This contrasts with the two-dimensional solution found for manmade hazards. Responsibility for risk management was found to be related to the type of risk in focus, and different risk characteristics seem to play different roles for manmade and natural hazards.     

Evaluating performance in continuous experiments with feedback to subjects

Consider an experiment in which a subject guesses repeatedly at a randomly chosen target on a continuum. To guarantee a positive probability of success, the continuum is partitioned into a finite but large number of segments. The subject is given directional feedback. General guessing strategies are characterized, and an optimal strategy is identified. The hypothesis that the subject's performance can be explained by chance alone is of interest in such experiments. A test is developed based on comparing the subject's performance to expected performance using the optimal strategy. A skill-scoring procedure is developed for assessing a subject's performance in light of the strategy used, and a test based on skill-scoring is advanced.Research by the first author is supported in part by the Air Force Office of Scientific Research under grant AFOSR 77-3180.The authors wish to thank the referees for remarks that led to improvements in both content and clarity.