“Extinction” of the McCollough effect does not transfer interocularly

A McCollough effect was induced in subjects by having them view typical adapting stimuli binocularly for 5 min. In the control condition, the strength of the McCollough effect was measured 20 min after the end of the adaptation. The strength was measured during monocular and binocular viewing of a test pattern via a color cancellation technique. Monocular strengths for the two eyes of a given subject were equal to each other and slightly weaker than the binocular strength. In the test condition, 15 min of the 20 min between adaptation and testing were spent monocularly viewing black and white gratings of the same orientation and spatial frequency as the adapting gratings. The strength of the effect as measured ipsilaterally was markedly decreased from that in the control condition. The strength of the effect as measured with the contralateral eye showed only a small decrease from that of the control condition. This finding is relevant to various models of the McCollough effect and related color aftereffects, especially those that posit a “learning” type of mechanism between achromatic spatial channels (which exhibit clear interocular transfer of various achromatic effects) and monocular color channels.     

Normal McCollough effect in Alzheimer's disease and global amnesia

The McCollough effect (ME), a long-lasting, pattern-contingent aftereffect in normal human vision, was examined in persons with known deficits in memory. We induced MEs in 11 subjects, 5 patients with various severities of Alzheimer's disease (AD), H.M. (a patient who has global amnesia due to bilateral medial temporal lobectomy and who has been studied for 35 years since his operation), and 5 control subjects. H.M. and the AD patients showed MEs of strength and duration comparable to those of the control subjects. These results demonstrate a dissociation between learning mechanisms that mediate recall and recognition versus mechanisms that mediate the ME. Furthermore, knowledge about the sites of neuropathology in H.M. and in AD are consistent with other sources of evidence implicating early visual areas, especially V1, as a critical locus of the ME.     

Making quantized images appear smooth: Tricks of the trade in vision research

Digital image-processing systems combined with color raster television technology are opening new worlds for the visual psychophysicist. Some of the inherent limitations and practical hazards of these technologies are explored. Techniques for circumventing some of the current limitations are presented, especially with regard to the issue of real-time variation of visual images.     

Relationships between personality variables and bizarreness effects in free recall

Relationships between 6 personality variables and each of 3 different measures of recall for bizarre and common sentences were examined. The personality variables investigated included measures of sensation seeking, novelty experiencing, desire for novelty, arousal-seeking tendency, social potency, and conservatism. Recall was measured in terms of sentences accessed, target words recovered per accessed sentence, and misplaced target words. The results indicated the typical pattern of bizarreness effects on recall and significant relationships between personality variables and these effects. Arousal seeking and conservatism were positively related to a bizarreness advantage in sentences accessed. Additionally, high social potency was related to the recovery of more details from common than bizarre sentences, and high desire for novelty was related to a greater bizarre misplacement effect. The results are discussed in terms of orienting and defensive responses to bizarreness.     

History and future directions of human brain mapping and functional neuroimaging

It has long been known that there is some degree of localisation of function in the human brain, as indicated by the effects of traumatic head injury. Work in the middle of the 20th century, notably the direct cortical stimulation of patients during neurosurgery, suggested that the degree and specificity of such localisation of function were far greater than had earlier been imagined. One problem with the data based on lesions and direct stimulation was that the work depended on the study of what were, by definition, damaged brains. During the second half of the 20th century, a collection of relatively non-invasive tools for assessing and localising human brain function in healthy volunteers has led to an explosion of research in what is often termed "Brain Mapping". The present article reviews some of the history associated with these tools, but emphasises the current state of development with speculation about the future.     

Dynamic stereo displays for research on the recovery of three-dimensional structure

Research issues that can be addressed by combining stereoscopic and kinetic depth displays include cue conflict and recalibration, mutual constraints, specialization of cues, and differential effects of disparity and kinetic depth on other perceptions, such as size constancy. Methods of producing dynamic stereoscopic displays are reviewed, especially displays combining stereoscopic with orthographic projections of rotation in depth. A sample personal computer program in Pas-cal is provided.     

Development, reliability, and validity of the Measure of Sexual Identity Exploration and Commitment (MOSIEC)

Four studies were conducted on the development and validation of the Measure of Sexual Identity Exploration and Commitment (MoSIEC). Exploratory factor analysis of an initial item pool yielded a 22-item measure with 4 distinct factors assessing commitment, exploration, sexual orientation identity uncertainty, and synthesis/integration. Exploratory factor analysis findings support the argument that sexual identity is a broad, multidimensional construct and that the MoSIEC assesses the construct of sexual identity in a manner consistent with J. E. Marcia's (1966) model of identity development. Confirmatory factor analyses demonstrated the stability of the MoSIEC factor structure, providing evidence of construct validity. Test-retest stability, internal consistency, and validity coefficients supported the use and continued development of the MoSIEC. Significant differences in levels of exploration and sexual orientation identity uncertainty were found among different sexual orientation identity groups, establishing the criterion-related validity of the MoSIEC. Implications for further development and use of the MoSIEC are discussed.     

Fading procedures and conditional discrimination in children

A discrimination reversal task followed by a conditional discrimination problem was administered to children (age range 36 to 107 months). A fading procedure was used during the discrimination reversal training of some subjects and other subjects were trained by a traditional procedure. More subjects trained by the fading procedure performed without errors during training and more subjects in the traditional group solved the conditional discrimination problem.