In four variants of a speeded target detection task, we investigated the processing of color and motion signals in the human visual system. Participants were required to attend to both a particular color and direction of motion in moving random dot patterns (RDPs) and to report the appearance of the designated targets. Throughout, reaction times (RTs) to simultaneous presentations of color and ...

Knowledge about the typical colors associated with familiar everyday objects (i.e., strawberries are red) is well-known to be represented in the conceptual semantic system. Evidence that such knowledge may also play a role in early perceptual processes for object recognition is scant. In the present ERP study, participants viewed a list of object pictures and detected infrequent stimulus repeti...

We have measured how color appearance of squarewave bars varies with stimulus strength and spatial frequency. Observer's adjusted the color of an uniform patch to match the color appearance of the bars in squarewave patterns. We used low to moderate squarewave patterns, from one to eight cycles per degree (cpd). The matches are not photoreceptor matches, but rather are established at more centr...

OBJECTIVES Manual response time (RT) and P300 event-related potential (ERP) measures were recorded in a Stroop color naming task to determine if previous results with vocal responses would be obtained using an arbitrary stimulus-response (S-R) mapping. METHODS Subjects (n = 32) were instructed to respond to the display color of a word but to ignore its meaning. Display color was congruent, ne...

25 Metacontrast is a visual illusion in which the visibility of a target stimulus is 26 virtually lost when immediately followed by a non-overlapping mask stimulus. 27 For a colored target, metacontrast is color-selective, with target visibility 28 markedly reduced when the mask and target are the same color, but only 29 slightly reduced when the colors differ. The present study investigated ne...

In event-related brain potential (ERP) studies of brain activity using a visual S1-S2 matching task, change stimuli elicit a posterior positive component with a latency of 100-200 ms. To elucidate the hierarchical organization of the processing of a visual stimulus change based on multiple stimulus features, ERPs were recorded in 12 participants performing an S1-S2 matching task with stimuli de...

We have studied the influence of chromatic adaptation upon the perceived visual position of a test stimulus using a Vernier alignment task. Maximum and minimum offsets in spatial position are generated when the adapting and test stimuli lie on the same and orthogonal axes in MBDKL color space, respectively. When the test stimuli lie on intermediate color axes, the measured positional shifts dec...

Associative color learning has been demonstrated to be very poor using restrained European honey bees unless the antennae are amputated. Consequently, our understanding of proximate mechanisms in visual information processing is handicapped. Here we test learning performance of Africanized honey bees under restrained conditions with visual and olfactory stimulation using the proboscis extension...

Metacontrast is a visual illusion in which the visibility of a target stimulus is virtually lost when immediately followed by a nonoverlapping mask stimulus. For a colored target, metacontrast is color-selective, with target visibility markedly reduced when the mask and target are the same color, but only slightly reduced when the colors differ. This study investigated neural correlates of colo...

Are effects of background contrast on color appearance and sensitivity controlled by the same mechanism of adaptation? We examined the effects of background color contrast on color appearance and on color-difference sensitivity under well-matched conditions. We linked the data using Fechner's hypothesis that the rate of apparent stimulus change is proportional to sensitivity and examined a fami...