Distractor Heterogeneity versus Linear Separability in Colour Visual Search

Perception ◽  
1996 ◽  
Vol 25 (11) ◽  
pp. 1281-1293 ◽  
Author(s):  
Ben Bauer ◽  
Pierre Jolicoeur ◽  
William B Cowan
Keyword(s):  
Visual Search ◽  
Search Display ◽  
Search Performance ◽  
Set Size ◽  
Linear Separability

D'Zmura, and Bauer, Jolicoeur, and Cowan demonstrated that a target whose chromaticity was linearly separable from distractor chromaticities was relatively easy to detect in a search display, whereas a target that was not linearly separable from the distractor chromaticities resulted in steep search slopes. This linear separability effect suggests that efficient colour visual search is mediated by a chromatically linear mechanism. Failure of this mechanism leads to search performance strongly influenced by number of search items (set size). In their studies, linear separability was confounded with distractor heterogeneity and thus the results attributed to linear separability were also consistent with the model of visual search proposed by Duncan and Humphreys in which search performance is determined in part by distractor heterogeneity. We contrasted the predictions based on linear separability and on the Duncan and Humphreys model by varying the ratios of the quantities of the two distractors and demonstrated the potent effects of linear separability in a design that deconfounded linear separability and distractor heterogeneity.

scholarly journals Predicting Search Performance in Heterogeneous Visual Search Scenes with Real-World Objects

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Zhiyuan Wang ◽  
Simona Buetti ◽  
Alejandro Lleras
Keyword(s):  
Visual Search ◽  
Real World ◽  
Visual Processing ◽  
Search Performance ◽  
Computational Simulations ◽  
Fixed Target ◽  
Set Size ◽  
Search Data ◽  
Exhaustive Processing ◽  
Processing Architecture

Previous work in our lab has demonstrated that efficient visual search with a fixed target has a reaction time by set size function that is best characterized by logarithmic curves. Further, the steepness of these logarithmic curves is determined by the similarity between target and distractor items (Buetti et al., 2016). A theoretical account of these findings was proposed, namely that a parallel, unlimited capacity, exhaustive processing architecture is underlying such data. Here, we conducted two experiments to expand these findings to a set of real-world stimuli, in both homogeneous and heterogeneous search displays. We used computational simulations of this architecture to identify a way to predict RT performance in heterogeneous search using parameters estimated from homogeneous search data. Further, by examining the systematic deviation from our predictions in the observed data, we found evidence that early visual processing for individual items is not independent. Instead, items in homogeneous displays seemed to facilitate each other’s processing by a multiplicative factor. These results challenge previous accounts of heterogeneity effects in visual search, and demonstrate the explanatory and predictive power of an approach that combines computational simulations and behavioral data to better understand performance in visual search.

scholarly journals Individual differences in visual search performance extend from artificial arrays to naturalistic environments.

2021 ◽  
Author(s):  
Thomas L. Botch ◽  
Brenda D. Garcia ◽  
Yeo Bi Choi ◽  
Caroline E. Robertson
Keyword(s):  
Individual Differences ◽  
Visual Search ◽  
Eye Movements ◽  
Real World ◽  
Search Task ◽  
Visual Search Task ◽  
Search Behavior ◽  
Search Performance ◽  
Set Size ◽  
Visual Clutter

Visual search is a universal human activity in naturalistic environments. Traditionally, visual search is investigated under tightly controlled conditions, where head-restricted participants locate a minimalistic target in a cluttered array presented on a computer screen. Do classic findings of visual search extend to naturalistic settings, where participants actively explore complex, real-world scenes? Here, we leverage advances in virtual reality (VR) technology to relate individual differences in classic visual search paradigms to naturalistic search behavior. In a naturalistic visual search task, participants looked for an object within their environment via a combination of head-turns and eye-movements using a head-mounted display. Then, in a classic visual search task, participants searched for a target within a simple array of colored letters using only eye-movements. We tested how set size, a property known to limit visual search within computer displays, predicts the efficiency of search behavior inside immersive, real-world scenes that vary in levels of visual clutter. We found that participants' search performance was impacted by the level of visual clutter within real-world scenes. Critically, we also observed that individual differences in visual search efficiency in classic search predicted efficiency in real-world search, but only when the comparison was limited to the forward-facing field of view for real-world search. These results demonstrate that set size is a reliable predictor of individual performance across computer-based and active, real-world visual search behavior.

Automatic Selection of Irrelevant Object Features Through Working Memory

2009 ◽  
Vol 56 (3) ◽  
pp. 165-172 ◽  
Author(s):  
David Soto ◽  
Glyn W. Humphreys
Keyword(s):  
Working Memory ◽  
Visual Search ◽  
Memory Task ◽  
Search Display ◽  
Target Line ◽  
Search Performance ◽  
Distractor Object ◽  
Automatic Selection ◽  
Object Features ◽  
Selection Of

Recent research has shown that the contents of working memory (WM) can guide the early deployment of attention in visual search. Here, we assessed whether this guidance occurred for all attributes of items held in WM, or whether effects are based on just the attributes relevant for the memory task. We asked observers to hold in memory just the shape of a coloured object and to subsequently search for a target line amongst distractor lines, each embedded within a different object. On some trials, one of the objects in the search display could match the shape, the colour or both dimensions of the cue, but this object never contained the relevant target line. Relative to a neutral baseline, where there was no match between the memory and the search displays, search performance was impaired when a distractor object matched both the colour and the shape of the memory cue. The implications for the understanding of the interaction between WM and selection are discussed.

scholarly journals Periodic attention operates faster during more complex visual search

2021 ◽  
Author(s):  
Garance Merholz ◽  
Laetitia Grabot ◽  
Rufin VanRullen ◽  
Laura Dugué
Keyword(s):  
Visual Search ◽  
Visual Processing ◽  
Visual Information ◽  
Temporal Dynamics ◽  
Task Complexity ◽  
Low Frequency ◽  
Search Performance ◽  
Set Size ◽  
Low Frequency Oscillations ◽  
Wide Range

AbstractAttention has been found to sample visual information periodically, in a wide range of frequencies below 20 Hz. This periodicity may be supported by brain oscillations at corresponding frequencies. We propose that part of the discrepancy in periodic frequencies observed in the literature is due to differences in attentional demands, resulting from heterogeneity in tasks performed. To test this hypothesis, we used visual search and manipulated task complexity, i.e., target discriminability (high, medium, low) and number of distractors (set size), while electro-encephalography was simultaneously recorded. We replicated previous results showing that the phase of pre-stimulus low-frequency oscillations predicts search performance. Crucially, such effects were observed at increasing frequencies within the theta-alpha range (6-18 Hz) for decreasing target discriminability. In medium and low discriminability conditions, correct responses were further associated with higher post-stimulus phase-locking than incorrect ones, in increasing frequency and latency. Finally, the larger the set size, the later the post-stimulus effect peaked. Together, these results suggest that increased complexity (lower discriminability or larger set size) requires more attentional cycles to perform the task, partially explaining discrepancies between reports of attentional sampling. Low-frequency oscillations structure the temporal dynamics of neural activity and aid top-down, attentional control for efficient visual processing.

The Speed of Visual Search in the Absence of Sensory Effects

Perception ◽  
1997 ◽  
Vol 26 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Jukka Saarinen
Keyword(s):  
Visual Search ◽  
Eye Movements ◽  
Search Time ◽  
Search Display ◽  
Serial Search ◽  
Set Size ◽  
Sensory Effects ◽  
Stimulus Block ◽  
Target Experiment ◽  
Target Locations

The purpose of this study was to investigate the efficiency or speed of the frequently used L versus T visual search when sensory effects were controlled, ie ‘set size’ was not defined as the number of distractor patterns, but the number of distractors in the display was kept constant and the number of possible target positions varied. A search display consisted of an L-target among T-distractors, and the observer's task was to report the presence or absence of the target (experiment 1) or to identify it (whether the L-target was left-facing or right-facing; experiment 2). The observer was instructed prior to each stimulus block, about the display locations in which the target could appear. In both experiments, search time increased significantly with an increasing number of possible target locations, thus indicating that L versus T search is not ‘serial’ owing to sensory effects. Because, in the first two experiments, a search display was visible until the observer gave a response, ‘serial’ search might have resulted just from eye movements. Therefore, a control experiment was run in which display duration was limited to 150 ms. The results of this experiment showed that, even when eye movements were prevented, the search still occurred ‘serially’, ie response time increased as a function of the number of possible target positions.

scholarly journals Beta and theta oscillations differentially support free versus forced control over multiple-target search

2018 ◽  
Author(s):  
Joram van Driel ◽  
Eduard Ort ◽  
Johannes J. Fahrenfort ◽  
Christian N. L. Olivers
Keyword(s):  
Visual Search ◽  
Eye Tracking ◽  
Search Display ◽  
Neural Mechanisms ◽  
Search Performance ◽  
Multiple Target ◽  
Proactive Control ◽  
Reactive Control ◽  
Target Search ◽  
Time Frequency

AbstractMany important situations require human observers to simultaneously search for more than one object. Despite a long history of research into visual search, the behavioral and neural mechanisms associated with multiple-target search are poorly understood. Here we test the novel theory that the efficiency of looking for multiple targets critically depends on the mode of cognitive control the environment affords to the observer. We used an innovative combination of EEG and eye tracking while participants searched for two targets, within two different contexts: Either both targets were present in the search display and observers were free to prioritize either one of them, thus enabling proactive control over selection; or only one of the two targets would be present in each search display, which requires reactive control to reconfigure selection when the wrong target is prioritized. During proactive control, both univariate and multivariate signals of beta-band (15–35 Hz) power suppression prior to display onset predicted switches between target selections. This signal originated over midfrontal and sensorimotor regions and has previously been associated with endogenous state changes. In contrast, imposed target selections requiring reactive control elicited prefrontal power enhancements in the delta/theta-band (2–8 Hz), but only after display onset. This signal predicted individual differences in associated oculomotor switch costs, reflecting reactive reconfiguration of target selection. The results provide compelling evidence that multiple target representations are differentially prioritized during visual search, and for the first time reveal distinct neural mechanisms underlying proactive and reactive control over multiple-target search.Significance StatementSearching for more than one object in complex visual scenes can be detrimental for search performance. While perhaps annoying in daily life, this can have severe consequences in professional settings such as medical and security screening. Previous research has not yet resolved whether multiple-target search involves changing priorities in what people attend to, and how such changes are controlled. We approached these questions by concurrently measuring cortical activity and eye movements using EEG and eye tracking, while observers searched for multiple possible targets. Our findings provide the first unequivocal support for the existence of two modes of control during multiple-target search, which are expressed in qualitatively distinct time-frequency signatures of the EEG both before and after visual selection.

The Influences of Goal and Laterality of a Prepared Hand Response on a Co-Occurring Visual Search

2015 ◽  
Vol 74 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Alexandre Coutté ◽  
Gérard Olivier ◽  
Sylvane Faure
Keyword(s):  
Visual Search ◽  
Visual Target ◽  
Motor Planning ◽  
Search Performance ◽  
Response Preparation ◽  
Manual Response ◽  
Response Hand ◽  
Computer Screen ◽  
Left Hand ◽  
Manual Interaction

Computer use generally requires manual interaction with human-computer interfaces. In this experiment, we studied the influence of manual response preparation on co-occurring shifts of attention to information on a computer screen. The participants were to carry out a visual search task on a computer screen while simultaneously preparing to reach for either a proximal or distal switch on a horizontal device, with either their right or left hand. The response properties were not predictive of the target’s spatial position. The results mainly showed that the preparation of a manual response influenced visual search: (1) The visual target whose location was congruent with the goal of the prepared response was found faster; (2) the visual target whose location was congruent with the laterality of the response hand was found faster; (3) these effects have a cumulative influence on visual search performance; (4) the magnitude of the influence of the response goal on visual search is marginally negatively correlated with the rapidity of response execution. These results are discussed in the general framework of structural coupling between perception and motor planning.

Sign in / Sign up

Export Citation Format

Share Document