scholarly journals Visual search of illusory contours: an attempt of automatization

Psihologija ◽  
2008 ◽  
Vol 41 (3) ◽  
pp. 295-309 ◽  
Author(s):  
Vasilije Gvozdenovic
Keyword(s):  
Visual Search ◽  
Experimental Research ◽  
Experimental Psychology ◽  
Illusory Contour ◽  
Task Type ◽  
Parallel Search ◽  
Illusory Contours ◽  
Serial Search ◽  
Experimental Trials ◽  
And Task

Laboratory of Experimental Psychology, University of Belgrade Recent research, which was mostly focused on assessing the types of visual search of illusory contours, showed that visual search is dependent on factors like target configuration and task type. Some experimental research supports the theory of parallel search while other research supports the theory of serial search of illusory contours. The inconsistency is most likely due to the fact that various types of illusory contour configurations were used in set creation. Up to this point, our research indicated that the serial search is used in most cases. Some exceptions of search type have been proven in some modification of task type but nevertheless the search profile remained serial. In this article, we are reporting on two visual search experiments. The first experiment was an investigation of a specific feature of a Kanisza type illusory triangle, orientation. The validity of the profile defined in the first experiment was tested in our second experiment with an attempt to automatize the visual search by the multiplication of the initial experimental trials. Our results confirmed that, regardless of the number of experimental trials, the visual search profile remains serial.

scholarly journals Form, set organization and visual attention in illusory contours perception

Psihologija ◽  
2009 ◽  
Vol 42 (2) ◽  
pp. 239-254 ◽  
Author(s):  
Vasilije Gvozdenovic
Keyword(s):  
Visual Search ◽  
Visual Attention ◽  
Experimental Psychology ◽  
Illusory Contours ◽  
Target Figure ◽  
Simple Detection ◽  
The Way

Laboratory of Experimental Psychology, University of Belgrade The aim of the study was the investigation of form, spatial set organization and visual attention in visual search of illusory contours. Three visual search experiments were conducted. In the first experiment, where the simple detection procedure was used, subject's task was to detect square among vertical and horizontal lines. Other experiments investigated visual search of illusory contours in four different set organizations. Introduction of set organization was the way of manipulation of target's eccentricity among other elements. Analysis showed different type of search of the regular and the illusory square figure. The search profile of the regular square proved to be parallel, while all the searches of the illusory squares remained serial. Set organization had important role in visual search of illusory contours. Regardless of serial profile, visual search was faster in cases where target figure was more salient due to the background elements organization.

Serial and Parallel Search in Pattern Vision?

Perception ◽  
1987 ◽  
Vol 16 (3) ◽  
pp. 389-398 ◽  
Author(s):  
Scott B Steinman
Keyword(s):  
Visual Search ◽  
Visual Field ◽  
Reaction Times ◽  
Positional Information ◽  
Human Vision ◽  
The Other ◽  
Parallel Search ◽  
Lateral Separation ◽  
Serial Search ◽  
Initial Results

The nature of the processing of combinations of stimulus dimensions in human vision has recently been investigated. A study is reported in which visual search for suprathreshold positional information—vernier offsets, stereoscopic disparity, lateral separation, and orientation—was examined. The initial results showed that reaction times for visual search for conjunctions of stereoscopic disparity and either vernier offsets or orientation were independent of the number of distracting stimuli displayed, suggesting that disparity was searched in parallel with vernier offsets or orientation. Conversely, reaction times for detection of conjunctions of vernier offsets and orientation, or lateral separation and each of the other positional judgements, were related linearly to the number of distractors, suggesting serial search. However, practice has a significant effect upon the results, indicative of a shift in the mode of search from serial to parallel for all conjunctions tested as well as for single features. This suggests a reinter-pretation of these and perhaps other studies that use the Treisman visual search paradigm, in terms of perceptual segregation of the visual field by disparity, motion, color, and pattern features such as colinearity, orientation, lateral separation, or size.

The Dynamics of Perceptual Learning in Different Visual Search Tasks: Psychophysics and Psychophysiology

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 232-232 ◽  
Author(s):  
U Leonards ◽  
R Rettenbach ◽  
R Sireteanu
Keyword(s):  
Visual Search ◽  
Reaction Time ◽  
Error Rate ◽  
Parallel Search ◽  
Additional Line ◽  
Serial Search ◽  
Search Tasks ◽  
Attentional Load ◽  
Skin Response ◽  
Perceptual Changes

Serial visual search can become parallel with practice (Sireteanu and Rettenbach, 1995 Vision Research35 2037 – 2043). Our purpose was to examine whether psychophysiological indices reflect the changes in reaction time during training. We used targets and distractors that differed either in orientation (‘tilt’), or in local brightness: closed circles with or without an additional line element (‘added line’), or circles with gaps of different width (‘gap’). The subjects’ task was to indicate the presence or absence of a target on a computer screen by immediately pressing a button and pointing to the location of the target if the trial was positive, or raise the hand if negative. No feedback was given. Response time and error rate were recorded. In addition, electrocardiograms, galvanic skin response, respiration rate and amplitude, horizontal eye movements, and electromyograms were monitored. Two naive and two experienced subjects participated in at least 16 experimental sessions. Before training, slopes differed for the three tasks, ranging from parallel search for the feature ‘tilt’ to a very steep serial search for the feature ‘gap’. These differences were reflected in the psychophysiological parameters. Reaction time and error rate decreased continuously with learning, leading to parallel search after prolonged practice for all three tasks (see Nase et al, 1995 Perception24 Supplement, 84). Preliminary results indicate that the psychophysiological measures do not follow the perceptual changes during learning. We conclude that, despite the perceptual parallelisation with practice, the attentional load remains high for initially serial tasks.

scholarly journals Color Can Shorten Breakthrough Times in Continuous Flash Suppression through Increased Salience and Task Relevance

Vision ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 13
Author(s):  
Christian Valuch
Keyword(s):  
Visual Search ◽  
Response Times ◽  
Top Down ◽  
Interocular Suppression ◽  
Continuous Flash Suppression ◽  
Task Relevance ◽  
Mediated Effects ◽  
Dominant Eye ◽  
Human Participants ◽  
And Task

Color can enhance the perception of relevant stimuli by increasing their salience and guiding visual search towards stimuli that match a task-relevant color. Using Continuous Flash Suppression (CFS), the current study investigated whether color facilitates the discrimination of targets that are difficult to perceive due to interocular suppression. Gabor patterns of two or four cycles per degree (cpd) were shown as targets to the non-dominant eye of human participants. CFS masks were presented at a rate of 10 Hz to the dominant eye, and participants had the task to report the target’s orientation as soon as they could discriminate it. The 2-cpd targets were robustly suppressed and resulted in much longer response times compared to 4-cpd targets. Moreover, only for 2-cpd targets, two color-related effects were evident. First, in trials where targets and CFS masks had different colors, targets were reported faster than in trials where targets and CFS masks had the same color. Second, targets with a known color, either cyan or yellow, were reported earlier than targets whose color was randomly cyan or yellow. The results suggest that the targets’ entry to consciousness may have been speeded by color-mediated effects relating to increased (bottom-up) salience and (top-down) task relevance.

There is No Evidence That Kanizsa-Type Subjective Contours Can Be Detected in Parallel

Perception ◽  
1996 ◽  
Vol 25 (7) ◽  
pp. 861-874 ◽  
Author(s):  
Rick Gurnsey ◽  
Frédéric J A M Poirier ◽  
Eric Gascon
Keyword(s):  
Visual Search ◽  
Control Problem ◽  
Search Task ◽  
Visual Search Task ◽  
Physiological Data ◽  
Sufficient Information ◽  
Parallel Search ◽  
High Contrast ◽  
Psychophysical Data ◽  
Area V2

Davis and Driver presented evidence suggesting that Kanizsa-type subjective contours could be detected in a visual search task in a time that is independent of the number of nonsubjective contour distractors. A linking connection was made between these psychophysical data and the physiological data of Peterhans and von der Heydt which showed that cells in primate area V2 respond to subjective contours in the same way that they respond to luminance-defined contours. Here in three experiments it is shown that there was sufficient information in the displays used by Davis and Driver to support parallel search independently of whether subjective contours were present or not. When confounding properties of the stimuli were eliminated search became slow whether or not subjective contours were present in the display. One of the slowest search conditions involved stimuli that were virtually identical to those used in the physiological studies of Peterhans and von der Heydt to which Davis and Driver wish to link their data. It is concluded that while subjective contours may be represented in the responses of very early visual mechanisms (eg in V2) access to these representations is impaired by high-contrast contours used to induce the subjective contours and nonsubjective figure distractors. This persistent control problem continues to confound attempts to show that Kanizsa-type subjective contours can be detected in parallel.

scholarly journals Attention capacity and task difficulty in visual search

Cognition ◽  
2005 ◽  
Vol 94 (3) ◽  
pp. B101-B111 ◽  
Author(s):  
Liqiang Huang ◽  
Harold Pashler
Keyword(s):  
Visual Search ◽  
Task Difficulty ◽  
And Task

Insect perception of illusory contours

1992 ◽  
Vol 337 (1279) ◽  
pp. 59-64 ◽  
Keyword(s):  
Human Visual System ◽  
Illusory Contour ◽  
Optic Lobe ◽  
Insect Vision ◽  
Local Contrast ◽  
Fault Line ◽  
Illusory Contours ◽  
Striped Pattern ◽  
Processing Power ◽  
As If

The human visual system sees an illusory contour where there is a fault line across a regular striped pattern. We demonstrate that bees respond as if they see the same illusory contour. There is also a type of neuron in the lobula of the dragonfly optic lobe which responds directionally to motion of the illusory contour as if to an edge or line. Apparently insects have a mechanism that sees illusory contours and therefore assists in the demarcation of edges and objects at places where local contrast falls to zero at an edge, or where one textured object partially obscures another. These results suggest that insect vision, although spatially crude and low in processing power, sees separate objects by similar mechanisms to our own.

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