Colour Mechanisms Underlying Visual Search with Heterochromatic Distractors

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 50-50
Author(s):  
H Yamamoto ◽  
Y Ejima
Keyword(s):  
Visual Search ◽  
Test Stimulus ◽  
Search Task ◽  
Visual Search Task ◽  
The Other ◽  
Chance Level ◽  
Central Angle ◽  
Colour Space ◽  
Target Direction

We studied the colour mechanisms involved in a visual search task. The test stimulus consisted of a coloured target randomly positioned among heterogeneous distractors of two colours. Colours of the target and distractors were specified in the equiluminous plane; a pair of distractors was set to lie on a circle around the target and characterised by the radius, central angle, and chromatic direction of a right bisector of the chord between the pair. The stimulus was presented briefly, and observers were asked to report whether a target was present. Target detectability quantified by d' depended on the central angle and the chromatic direction of the bisector. The central angle affected the detectability of the coloured target but not that of the white one. The coloured-target detectability decreased and reached chance level with increasing central angle from 0° to 180°. For a fixed obtuse central angle, maxima of the coloured-target detectability occurred at two bisector directions, one orthogonal to the target direction and the other along the target direction. This suggests that only two orthogonal colour mechanisms were at play and they changed with the colour of the target. These results and previous findings that the target was detected preattentively when it was linearly separable from the distractors in colour space (D'Zmura, 1991 Vision Research31 951 – 966; Bauer et al, 1996 Vision Research36 1439 – 1465) may be explained by the same processes, colour selective filters that linearly combine cone signals followed by peak detectors.

Influence of Selection Difficulty on the Time Required for Icon Formation

Perception ◽  
1976 ◽  
Vol 5 (2) ◽  
pp. 225-231
Author(s):  
Robert T Solman
Keyword(s):  
Information Processing ◽  
Visual Search ◽  
Search Task ◽  
Visual Search Task ◽  
Probability Distributions ◽  
Target Selection ◽  
The Other ◽  
Cumulative Probability ◽  
Physical Similarity ◽  
Time Required

By increasing the number of display items and the physical similarity between the target and the irrelevant items it was possible to vary the difficulty of target selection in a visual-search task. The results showed that the accuracy with which the target was located declined as target selection became more difficult. On the other hand, estimates of the cumulative probability and the probability distributions of times necessary to form the icon indicated that these times were not influenced by changes in the difficulty of the task. The latter result supports Neisser's suggestion that the information processing carried out during the first stage of analysis can be attributed to the action of a distinct cognitive mechanism.

Visual Search Using Microfiche: Effects of Microfiche Reader Screen Scintillation on Visual Fatigue, General Fatigue, and Performance

1978 ◽  
Vol 22 (1) ◽  
pp. 299-302 ◽  
Author(s):  
William H. Cushman
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Visual Search Task ◽  
The Other ◽  
Visual Fatigue ◽  
General Fatigue ◽  
Dependent Variables ◽  
And Performance

Nine subjects performed a visual search task for two 100-minute sessions using microfiche with positive appearing images and small, portable microfiche readers. During one session the subjects performed the task with a reader having a screen with highly visible scintillation. During the other they used a reader equipped with a screen that was nearly free from scintillation. Dependent variables were subjective visual fatigue, general fatigue, and number of targets located. Subjects reported significantly greater visual fatigue after viewing the “high” scintillation screen for 50–100 minutes than after viewing the “low” scintillation screen for the same length of time. When the high-scintillation screen was used, the subjects also reported an increase in general fatigue. Screen scintillation did not affect the subjects' performance on the search task, however.

scholarly journals Working memory implements distinct maintenance mechanisms depending on task goals

2017 ◽  
Author(s):  
Johannes J. Fahrenfort ◽  
Jonathan Van Leeuwen ◽  
Joshua J. Foster ◽  
Edward Awh ◽  
Christian N.L. Olivers
Keyword(s):  
Working Memory ◽  
Visual Search ◽  
Search Task ◽  
Visual Search Task ◽  
Recall Task ◽  
Neural Mechanisms ◽  
The Other ◽  
Informational Content ◽  
Current Task ◽  
Task Goals

AbstractWorking memory is the function by which we temporarily maintain information to achieve current task goals. Models of working memory typically debate where this information is stored, rather than how it is stored. Here we ask instead what neural mechanisms are involved in storage, and how these mechanisms change as a function of task goals. Participants either had to reproduce the orientation of a memorized bar (continuous recall task), or identify the memorized bar in a search array (visual search task). The sensory input and retention interval were identical in both tasks. Next, we used decoding and forward modeling on multivariate electroencephalogram (EEG) and time-frequency decomposed EEG to investigate which neural signals carry more informational content during the retention interval. In the continuous recall task, working memory content was preferentially carried by induced oscillatory alpha-band power, while in the visual search task it was more strongly carried by the distribution of evoked (consistently elevated and non-oscillatory) EEG activity. To show the independence of these two signals, we were able to remove informational content from one signal without affecting informational content in the other. Finally, we show that the tuning characteristics of both signals change in opposite directions depending on the current task goal. We propose that these signals reflect oscillatory and elevated firing-rate mechanisms that respectively support location-based and object-based maintenance. Together, these data challenge current models of working memory that place storage in particular regions, but rather emphasize the importance of different distributed maintenance signals depending on task goals.Significance statement (120 words)Without realizing, we are constantly moving things in and out of our mind’s eye, an ability also referred to as ‘working memory’. Where did I put my screwdriver? Do we still have milk in the fridge? A central question in working memory research is how the brain maintains this information temporarily. Here we show that different neural mechanisms are involved in working memory depending on what the memory is used for. For example, remembering what a bottle of milk looks like invokes a different neural mechanism from remembering how much milk it contains: the first one primarily involved in being able to find the object, and the other one involving spatial position, such as the milk level in the bottle.

Disruption and Maintenance of Skilled Visual Search as a Function of Degree of Consistency

1993 ◽  
Vol 35 (2) ◽  
pp. 205-220 ◽  
Author(s):  
Mark D. Lee ◽  
Arthur D. Fisk
Keyword(s):  
Visual Search ◽  
Present Experiment ◽  
Search Task ◽  
Visual Search Task ◽  
The Other ◽  
Second Phase ◽  
Consistent Mapping ◽  
Practical Implications

The present experiment was conducted to investigate the effects of varying degrees of task consistency on the performance and maintenance of skill in a semanticcategory visual search task. Four groups of participants first received 6000 trials of consistent mapping (CM) training on two different categories. The participants then performed 4000 trials in which one of the previously trained categories remained 100% consistent, whereas the other previously trained category became either 100%, 67%, 50%, or 33% consistent. This second phase of the experiment allowed for the examination of disruption of the search skill as a function of degree of consistency. Subsequent to the degree of consistency manipulation, 100% consistency was restored and participants performed another 4200 CM trials. Results indicate that performance was disrupted by inconsistency and that disruption increased as consistency decreased. On the return of task consistency, performance improved rapidly to predisruption levels, though some performance disruption was evident. Theoretical and practical implications are discussed.

scholarly journals The persistence of value-driven attention capture is task dependent

2020 ◽  
Author(s):  
Anne Milner ◽  
Mary MacLean ◽  
Barry Giesbrecht
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Visual Search Task ◽  
Attention Capture ◽  
The Other ◽  
Visual Features ◽  
Capture Effect ◽  
Bias Attention ◽  
Task Irrelevant

Visual features previously associated with reward can automatically capture attention even when task-irrelevant, a phenomenon known as value-driven attention capture (VDAC, Anderson et al., 2011b). VDAC persists without reinforcement, unlike other forms of learning where removing reinforcement typically leads to extinction (Pavlov, 1927). This study examined the conditions under which VDAC could be extinguished. In four experiments, factors known to affect attention were manipulated to examine their impact on VDAC and its extinction. All experiments included learning and test phases. During learning, participants completed a visual search task during which one of two target colors was associated with a reward, and the other with no reward. During test, one week later, participants completed another visual search task during which the reward association was not reinforced. The task during test had twice as many exposures to the rewarded feature than during learning to ensure a sufficient number of exposures to observe extinction. When a rewarded feature remained task-relevant (Exp. 1), the capture effect was reduced, but extinction was not complete. When a rewarded feature was made task-irrelevant (Exp. 2) there was no evidence of extinction. When the frequency of exposure to the task-irrelevant rewarded feature was reduced (Exp. 4), VDAC also persisted. A physically salient target (Exp. 3) resulted in the fastest rate of VDAC extinction. These findings demonstrate that the extinction of VDAC depends on various factors that affect priority for attention, especially those that bias attention away from reward-associated features.

Degree of Task Consistency and Maintenance of Skill Level in Semantic Category Visual Search

1992 ◽  
Vol 36 (17) ◽  
pp. 1311-1315
Author(s):  
Mark D. Lee
Keyword(s):  
Visual Search ◽  
Present Experiment ◽  
Search Task ◽  
Visual Search Task ◽  
Skill Development ◽  
Semantic Category ◽  
Skill Level ◽  
The Other ◽  
Training Phase ◽  
Training Design

The present experiment investigated the effect of varying the degree of task consistency on the performance and maintenance of skill in a semantic category visual search task. It is well established that for a wide variety of tasks, skill development is a function of the degree of task consistency. However, the effect of inconsistency on established skills has not been investigated to date. The present experiment included a consistent Training Phase, an Adjusted Consistency Phase, and a Retraining Phase. Subjects were trained for 6,000 Consistently Mapped (CM) trials on two different categories. Subjects then performed 4,000 trials in which one of the previously trained categories remained 100% consistent, while the other category became either 100, 67, 50, or 33% consistent. Task consistency was then restored and participants performed another 4,200 CM trials. The Retraining Phase included a New CM category. Results indicated that performance was disrupted by inconsistency, and that disruption increased as consistency decreased. Upon the return of task consistency, performance improved rapidly, although some performance disruption was still evident. The results are discussed in terms of visual search theories, and for their relation to training design.

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