立体视觉的心理物理和VEP比较研究

心理物理试验是研究立体视觉的主要方法。70年代VEP开始用于体视研究,并取得许多结果。由于VEP信号复杂,这些结果不能令人满意。本文使用心理物理试验和VEP对比方法对体视加以研究。我们的结果是:VEP波形中第一个正峰与刺激图形的亮度有关;N_2峰和P_3峰的潜伏期对判断体视存在与否有重要价值;本试验确定N_2峰潜伏期在体视存在时约为240ms—280ms,无体视存在时约为290ms—310ms;P_3峰潜伏期在体视存在时约为280ms—310ms,无体视存在时约为340ms—360ms;体视存在时的VEP与无体视存在时的VEP的互相关系数小于0.1;有体视的VEP其功率谱密度在8Hz附近有一峰;心理物理试验中使用强制选择得到的结果从VEP波形比较中可以确认是可靠的;有体视的VEP其N_2和P_3的潜伏期随视差变化呈现规律性改变。     

Similarities derived from 3-d nonlinear psychophysics: Variance distributions

Many-one mappings between stimulus properties and pairwise generated similarities are intrinsic to definitions of similarity. This of itself is not sufficient as a basis for predicting the variance associated with any single similarity judgment. An extension to cover this has to be made either by making ancillary assumptions about noise, or by using nonlinear models. The derivation of the variance of similarity judgments is made from the 3 process in nonlinear psychophysics. The idea of separability of dimensions in metric space theories of similarity is replaced by one parameter which represents the degree of a form of interdimensional crosscoupling     

“Age-associated memory impairment”: A critique

Abstract

This paper is a critical evaluation of the construct of age-associated memory impairment (AAMI) and the criteria for assigning the AAMI label. It is argued that AAMI should not be regarded as a clinical diagnosis; that the AAMI criteria fail to isolate selective memory impairments, ignore crucial longitudinal information, and are vague, arbitrary, and unreliable; that studies of memory loss should examine a wider range of subjects than those who meet the AAMI criteria-moreover, use of the criteria may impede research; and that treatment studies should await investigations of the biological antecedents of memory loss. Several recommendations address subject selection and assessment issues.     

Effects of the range and frequency of vibrations on the momentary riding comfort evaluation of a railway vehicle

When trains pass level-crossings, turnouts, and rail joints, they are momentarily subjected to extreme vibrations. In railway engineering, evaluation of the riding comfort under such occasional vibrations is called the momentary riding comfort evaluation, as distinct from the long-term evaluation, which addresses the riding comfort of passengers for certain lengths of train operation. In order to identify the effective vibrational characteristics of the momentary evaluation, an experiment was performed with a riding comfort simulator. Ten adult subjects for each condition, 80 in total, participated in the experiment. The effects of differences in the range of stimuli, frequency of each stimulus, and scores on a rating scale of discomfort were studied. Differences in the range and frequency affected the evaluation such that subjects tended to make a relative judgment on discomfort. They made almost an absolute judgment when the rating scale was well defined, with a small number of categories.     

Weigh(t)ing for Awareness

We wished to learn if weight perception can be extinguished by studying two patients with right hemisphere brain damage. When lifting weights simultaneously, a patient with right frontal damage was not biased in her judgments of which weight was heavier. By contrast, a patient with right parietal damage reported left-sided weights as being lighter than those on the right. Psychophysical power functions revealed that her awareness of increasing weights on the left was dampened compared to the right when lifting weights individually on each side. Strikingly, her awareness of weight changes on the left was completely abolished when she lifted weights in both hands simultaneously. She demonstrated an unusual split in awareness, being motorically aware of and actively engaged with left-sided weights while being unaware of their incremental changes.     

Perceptual learning effect on decision and confidence thresholds

Practice can enhance of perceptual sensitivity, a well-known phenomenon called perceptual learning. However, the effect of practice on subjective perception has received little attention. We approach this problem from a visual psychophysics and computational modeling perspective. In a sequence of visual search experiments, subjects significantly increased the ability to detect a “trained target”. Before and after training, subjects performed two psychophysical protocols that parametrically vary the visibility of the “trained target”: an attentional blink and a visual masking task. We found that confidence increased after learning only in the attentional blink task. Despite large differences in some observables and task settings, we identify common mechanisms for decision-making and confidence. Specifically, our behavioral results and computational model suggest that perceptual ability is independent of processing time, indicating that changes in early cortical representations are effective, and learning changes decision criteria to convey choice and confidence.     

NATURALISTIC METHODOLOGY IN AN EMERGING SCIENTIFIC PSYCHOLOGY: LOTZE AND FECHNER IN THE BALANCE

The development of a methodologically naturalistic approach to physiological and experimental psychology in the nineteenth century was not primarily driven by a naturalistic agenda. The work of R. Hermann Lotze and G. T. Fechner help to illustrate this claim. I examine a selected set of central commitments in each thinkers philosophical outlook, particularly regarding the human soul and the nature of God, that departed strongly from a reductionist materialism. Yet, each contributed significantly to the formation of experimental and physiological psychology. Their work was influenced substantively by their respective philosophical commitments. Nevertheless, the evaluation of the merits of their specific proposals, Fechner's psychophysics and Lotze's local sign hypothesis respectively, did not depend upon sharing their metaphysical views regarding the human soul or the nature of God. A moderate, but significant, distinction between the contexts of discovery and of justification aids in understanding this balancing act.     

Low-dose caffeine discrimination and self-reported mood effects in normal volunteers.

A caffeine versus placebo discrimination procedure was used to determine the lowest caffeine dose that could produce discrimination and self-reported mood effects in normal volunteers. During daily sessions under double-blind conditions, caffeine-abstinent subjects orally ingested a capsule containing 178 mg caffeine or placebo. Before beginning discrimination training, the compounds were identified to subjects by letter codes. Fifteen, 30, and 45 min after capsule ingestion, subjects guessed the capsule's letter code. Correct guesses at 45 min earned money. After each session, subjects received a supplementary capsule containing caffeine or placebo to ensure that, within each phase of the study, subjects received the same daily dose of caffeine equal to the training dose. Five of the 15 subjects acquired the caffeine versus placebo discrimination within the first 20 sessions (greater than or equal to 75% correct); 6 other subjects acquired the discrimination with additional training. Nine subjects who acquired the discrimination were subsequently trained at progressively lower caffeine doses. In general, the lowest dose to produce discrimination (greater than or equal to 75% correct) was also the lowest dose to produce self-reported mood effects: 4 subjects showed discrimination and self-reported mood effects at 100 mg caffeine, 2 at 56 mg, 1 at 32 mg, and 1 at 18 mg. One of these subjects also showed self-reported mood effects at 10 mg. The present study documents discriminative stimulus and self-reported mood effects of caffeine at doses below those previously shown to affect any behavior in normal volunteers.     

Temporal discrimination and a free-operant psychophysical procedure.

Pigeons were presented a series of keylight time periods (separated by blackouts) during which two response keys were lit, one by blue light and the other either by orange or green. Blue-key responses changed the color on the other key. Orange-key responses sometimes produced food during the first half of a time period; green-key responses sometimes produced food during the second half. In three experiments, the probability of a green-key response increased as a function of elapsed time. Experiment 1 compared performance when the duration of the keylight periods was varied across a wide range. Discrimination of performance was similar across the range of durations. Experiment 2 varied both relative reinforcement rate and the local reinforcement rate for orange-key and green-key responses. These manipulations produced changes in response bias but not discrimination sensitivity. Experiment 3 varied the local temporal placement of reinforcers within time periods and demonstrated that choice behavior was affected by differential reinforcement at different points during the time periods. The results were consistent with previous research on duration discrimination that used psychophysical trials procedures.