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Publications (185)
Visual search is a ubiquitous behavior among sighted organisms. The study of visual search in humans has a rich history in cognitive psychology and allied fields going back over a century. Visual search paradigms have been used to probe the nature of the visual system for decades. However, these studies were predominantly characterized by a single...
Medical image interpretation is central to detecting, diagnosing, and staging cancer and many other disorders. At a time when medical imaging is being transformed by digital technologies and artificial intelligence, understanding the basic perceptual and cognitive processes underlying medical image interpretation is vital for increasing diagnostici...
We investigated whether standardized neuropsychological tests and experimental cognitive paradigms measure the same cognitive faculties. Specifically, do neuropsychological tests commonly used to assess attention measure the same construct as attention paradigms used in cognitive psychology and neuroscience? We built on the “general attention facto...
The Trail Making Test (TMT) is a common tool for neuropsychological assessment, both in the clinic and the laboratory. A key outcome is the time cost for TMT-B compared to TMT-A. Here we report new evidence for the involvement of working memory and inhibitory processing during TMT-B performance, based on data from the Multi-Item Localisation (MILO)...
Radiologists can identify whether a radiograph is abnormal or normal at above chance levels in breast and lung images presented for half a second or less. This early perceptual processing has only been demonstrated in static two-dimensional images (e.g., mammograms). Can radiologists rapidly extract the "gestalt" from more complex imaging modalitie...
This paper introduces a mobile app version of the Multi-Item Localization (MILO) task. The MILO task was designed to explore the temporal context of search through a sequence and has proven useful in both basic and applied research settings. Here, we describe the basic features of the app, how it can be obtained, installed and modified. We also pro...
A large body of evidence indicates that cancer survivors who have undergone chemotherapy have cognitive impairments. Substantial disagreement exists regarding which cognitive domains are impaired in this population. We suggest that is in part due to inconsistency in how neuropsychological tests are assigned to cognitive domains. The purpose of this...
Objectives:
To document challenges to and benefits from research involving the use of images by capturing examples of such research to assess physical activity- or nutrition-related behaviors and/or environments.
Methods:
Researchers (i.e., key informants) using image capture in their research were identified through knowledge and networks of th...
In visual search tasks, observers can guide their attention towards items in the visual field that share features with the target item. In this series of studies, we examined the time course of guidance toward a subset of items that have the same color as the target item. Landolt Cs were placed on 16 colored disks. Fifteen distractor Cs had gaps fa...
Cancer-related cognitive impairment (CRCI) is a widespread problem for the increasing population of cancer survivors. Our understanding of the nature, causes, and prevalence of CRCI is hampered by a reliance on clinical neuropsychological methods originally designed to detect focal lesions. Future progress will require collaboration between neurosc...
BACKGROUND
Image based data collection for obesity research is in its infancy.
OBJECTIVE
The present study aimed to document challenges to and benefits from such research by capturing examples of research involving the use of images to assess physical activity- or nutrition-related behaviors and/or environments.
METHODS
Researchers (i.e., key inf...
In this article we will present evidence that attention modulates awareness, but we have some awareness of unattended stimuli. Specifically, we will argue that attention is needed to solve the binding problem. Without attention, one can be aware of what object attributes are present in the scene, which allows for a surprising level of visual awaren...
(Current Biology 24, 1133–1137; May 19, 2014) It has been brought to our attention that this article contains a previously undetected but significant labeling error: we mislabeled two waveforms in Figure S3D of the Supplemental Information available online, such that the Vertical Target Waveforms were placed in the position labeled “Vertical Source...
One of the most important applications of visual search is in the interpretation of medical images. Like many applications of visual search, medical image interpretation is typically characterized as a low “prevalence” context, meaning that targets are relatively rare. Breast cancer screening, for example, has a prevalence of around 0.5%. In this r...
How do we find what we are looking for? Even when the desired target is in the current field of view, we need to search because fundamental limits on visual processing make it impossible to recognize everything at once. Searching involves directing attention to objects that might be the target. This deployment of attention is not random. It is guid...
Recent years have seen an explosion in the use of medical informatics, the application of computing power to medicine. This development has created great opportunities for improving the science and practice of oncology and cancer care, as illustrated in many other chapters in this volume. In principle, getting more information faster should let us...
In hybrid search, observers search through arrays of visually presented items for any of a set of targets held in memory; think of looking on a store shelf for items on your grocery list, searching luggage x-rays for potential banned items, or chest x-rays for signs of cancer. As the size of the memory sets used in hybrid search increased, descript...
While the relationship between action and focused attention has been well-studied, less is known about the ability to divide attention while acting. In the current paper we explore this issue using the multiple object tracking (MOT) paradigm (Pylyshyn & Storm, 1988). We asked whether planning and executing a display-relevant action during tracking...
Visual search is the study of how humans find desired objects in their visual environment. I provide brief outline of work on visual search, and then describe work on specific topics such as the effects of target prevalence and visual foraging. © 2014 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.
Each cerebral hemisphere initially processes one half of the visual world. How are moving objects seamlessly tracked when they traverse visual hemifields? Covert tracking of lateralized objects evokes a difference between slow-wave electrophysiological activity observed from contralateral and ipsilateral electrodes in occipitoparietal regions. This...
The ability of visually impaired people to deploy attention effectively to maximize use of their residual vision in dynamic situations is fundamental to safe mobility. We conducted a pilot study to evaluate whether tests of dynamic attention (multiple object tracking; MOT) and static attention (Useful Field of View; UFOV) were predictive of the abi...
We introduce a new task for exploring the relationship between action and attention. In this interactive multiple object tracking (iMOT) task, implemented as an iPad app, participants were presented with a display of multiple, visually identical disks which moved independently. The task was to prevent any collisions during a fixed duration. Partici...
Background / Purpose:
A previously published meta-analysis (1) suggested that chemotherapy did not lead to persistent deficits in the cognitive domain of attention. However, they did not use appropriate measures of attention.
Main conclusion:
I identified attention tests from the studies reported in the meta-analysis. Specifically, I pulled ou...
Consider a radiologist searching a mammogram for tumors, a baggage screener searching for weapons, or an intelligence analyst poring over satellite imagery of North Korea. In each of these visual search tasks, each image contains an unknown number of targets and there are many images to get through. How do observers choose when to move to the next...
Contour interpolation automatically binds targets with distractors to impair multiple object tracking (Keane, Mettler, Tsoi, & Kellman, 2011). Is interpolation special in this regard or can other features produce the same effect? To address this question, we examined the influence of eight features on tracking: color, contrast polarity, orientation...
A previous study reported the misbinding illusion in which visual features belonging to overlapping sets of items were erroneously integrated (Wu, Kanai, & Shimojo, 2004, Nature, 429, 262). In this illusion, central and peripheral portions of a transparent motion field combined color and motion in opposite fashions. When observers saw such stimuli,...
Many socially important search tasks are characterized by low target prevalence, meaning that targets are rarely encountered. For example, transportation security officers (TSOs) at airport checkpoints encounter very few actual threats in carry-on bags. In laboratory-based visual search experiments, low prevalence reduces the probability of detecti...
In the multiple object tracking task, participants are asked to keep targets separate from identical distractors as all items move randomly. It is well known that simple manipulations such as object speed and number of distractors dramatically alter the number of targets that are successfully tracked, but very little is known about what causes this...
Search for multiple targets is constrained by both retrospective (i.e., where you've been) and prospective (i.e., where you're planning to go) components of performance. Previous studies using the Multi-Item Localisation (MILO) task have demonstrated that participants accurately remember and discount locations they have already visited and that the...
Background / Purpose:
The purpose of this study was to determine whether perceptual organization could modulate visual search for outliers in the temporal frequency domain.
Main conclusion:
We found that, while reaction times and errors decreased with target-distractor distance (both for higher and lower frequency targets), search efficiency (...
How does the visual system use speed to guide visual search? According to the absolute speed hypothesis, the fastest moving object in the environment will be the most salient and will be found most efficiently. This hypothesis is supported by search asymmetry studies showing that moving targets are found more efficiently among stationary distractor...
The nature of capacity limits (if any) in visual search has been a topic of controversy for decades. In 30 years of work, researchers have attempted to distinguish between two broad classes of visual search models. Attention-limited models have proposed two stages of perceptual processing: an unlimited-capacity preattentive stage, and a limited-cap...
A typical visual scene we encounter in everyday life is complex and filled with a huge amount of perceptual information. The term, 'visual attention' describes a set of mechanisms that limit some processing to a subset of incoming stimuli. Attentional mechanisms shape what we see and what we can act upon. They allow for concurrent selection of some...
In everyday life, we often need to track several objects simultaneously, a task modeled in the laboratory using the multiple-object tracking (MOT) task [Pylyshyn, Z., & Storm, R. W. Tracking multiple independent targets: Evidence for a parallel tracking mechanism. Spatial Vision, 3, 179–197, 1988]. Unlike MOT, however, in life, the set of relevant...
Background / Purpose:
How does the visual system segregate moving and stationary objects? We tested three hypotheses: the motion filter hypothesis, the transient vs. sustained channel hypothesis, and the velocity channel hypothesis.
Main conclusion:
Data from five different experiments rejected the first two hypotheses, leaving the velocity ch...
Background / Purpose:
Do we need to assume capacity limitations to explain visual search performance on simple tasks? Attention-limited models propose two qualitatively different stages of perceptual processing: an unlimited capacity preattentive stage and a limited-capacity selective attention stage. Noise-limited decision models propose a singl...
Experiments have shown that people can rapidly determine if categories such as "animal" or "beach" are present in scenes that are presented for only a few milliseconds. Typically, observers in these experiments report on one prespecified category. For the first time, we show that observers can rapidly extract information about multiple categories....
Which coordinate system do we use to track moving objects? In a previous study using smooth pursuit eye movements, we argued that targets are tracked in both retinal (retinotopic) and scene-centered (allocentric) coordinates (Howe, Pinto, & Horowitz, 2010). However, multiple object tracking typically also elicits saccadic eye movements, which may c...
Numerous studies have shown that musicians outperform nonmusicians on a variety of tasks. Here we provide the first evidence that musicians have superior auditory recognition memory for both musical and nonmusical stimuli, compared to nonmusicians. However, this advantage did not generalize to the visual domain. Previously, we showed that auditory...
Observers are poor at reporting the identities of objects that they have successfully tracked (Pylyshyn, Visual Cognition, 11, 801-822, 2004; Scholl & Pylyshyn, Cognitive Psychology, 38, 259-290, 1999). Consequently, it has been claimed that objects are tracked in a manner that does not encode their identities (Pylyshyn, 2004). Here, we present evi...
In gunfights in Western movies, the hero typically wins, even though the villain draws first. Niels Bohr (Gamow, The great physicists from Galileo to Einstein. Chapter: The law of quantum, 1988) suggested that this reflected a psychophysical law, rather than a dramatic conceit. He hypothesized that reacting is faster than acting. Welchman, Stanley,...
This article illustrates a dissociation between the perceived attributes of an object and the ability of those attributes to guide the deployment of attention in visual search. Orientation is an attribute that guides search. Thus, a vertical line will "pop out" amid horizontal distractors. Amodal completion can create perceptually convincing orient...
The evidence is mixed as to whether the visual system treats objects and holes differently. We used a multiple object tracking task to test the hypothesis that figural objects are easier to track than holes. Observers tracked four of eight items (holes or objects). We used an adaptive algorithm to estimate the speed allowing 75% tracking accuracy....
In the attentive tracking task, observers track multiple objects as they move independently and unpredictably among visually identical distractors. Although a number of models of attentive tracking implicate visual working memory as the mechanism responsible for representing target locations, no study has ever directly compared the neural mechanism...
Existing tests (e.g., useful field of view; UFOV) that are commonly used to evaluate visual attention when predicting at-risk drivers do not have a dynamic component. In this project, we developed a brief computerized test of dynamic visual attention (multiple object tracking; MOT). Estimates of threshold tracking speed from the brief MOT test show...
In general, humans have impressive recognition memory for previously viewed pictures. Many people spend years becoming experts in highly specialized image sets. For example, cytologists are experts at searching micrographs filled with potentially cancerous cells and radiologists are expert at searching mammograms for indications of cancer. Do these...
Purpose: Research has shown that observers can track 4 or 5 out of 10 identical moving items. Pylyshyn proposed a spatial indexing theory in which a limited set of 4 or 5 spatial indices can be assigned to objects in the visual field. Yantis proposed that the tracked objects are grouped together and attended to as a single deforming object. These a...
We examined retrospective and prospective memory effects in a multiple-target, visuomotor search. Before each trial, subjects were given a cue sequence consisting of 4 target letters in immediate alphabetical order. They were then shown a search display of 8 letters: the 4 cued targets and 4 distractors. The letters were centered in 8 disks which w...
Many visual search experiments measure response time (RT) as their primary dependent variable. Analyses typically focus on mean (or median) RT. However, given enough data, the RT distribution can be a rich source of information. For this paper, we collected about 500 trials per cell per observer for both target-present and target-absent displays in...
Subjects in even simple visual search tasks often produce RT distributions with long positive tails. Typically, these long RTs are treated as noise resulting from vigilance or motor errors and are discarded. We propose instead that the skewed shape of RT distributions might tell us about the underlying cognitive architecture. These distributions tu...
Theories of visual search have generally assumed that rejected distractors are marked so as to avoid further processing of these items (memory-driven search). To test this assumption, Horowitz and Wolfe (1998) developed the randomized search paradigm, in which standard static search is compared to dynamic search in which items are randomly replotte...
We had observers perform an attentional gating task (Shih & Sperling, 2002) that required them to monitor a central 9.4 Hz RSVP stream for a cue digit. The identity of the digit instructed them to shift attention to one of two flanking streams and report the first letter they saw in that second stream. Attentional reaction time (ART) was defined as...
Both multiple-object visual tracking (MVT) and inefficient visual search are held to demand visual attention. However, we have previously shown (ARVO 2000) that both tasks can be performed concurrently within a single trial with minimal performance loss on either task. How is this possible? Here we test the hypothesis that observers switch back and...
Since Neisser (1967) and Treisman & Gelade (1980) many models of selective visual attention have included a preattentive stage of processing. Some researchers have suggested that the term "preattentive" has outlived its usefulness. While there are uses of "preattentive" that should be avoided, we argue against abandoning the concept altogether. If...
Is multiple object tracking (MOT) limited by a fixed set of structures (slots), a limited but divisible resource, or both? Here, we answer this question by measuring the precision of the direction representation for tracked targets. The signature of a limited resource is a decrease in precision as the square root of the tracking load. The signature...
Tracking moving objects is a fundamental attentional operation. Here we ask which coordinate system is used to track objects: retinal (retinotopic), scene-centered (allocentric), or both? Observers tracked three of six disks that were confined to move within an imaginary square. By moving either the imaginary square (and thus the disks contained wi...
Is it easier to track objects that you have seen repeatedly? We compared repeated blocks, where identities were the same from trial to trial, to unrepeated blocks, where identities varied. People were better in tracking objects that they saw repeatedly. We tested four hypotheses to explain this repetition benefit. First, perhaps the repeated condit...
Most accounts of multiple object tracking (MOT) suggest that only the spatial arrangement of objects at any one time is important for explaining performance. In contrast, we argue that observers predict future target positions. Previously this proposition was tested by studying the recovery of targets after a period of invisibility (Fencsik, Kliege...
People are generally able to track 4-5 objects as they move amongst visually identical distractors. However, Alvarez & Cavanagh (2005) found that if tracked objects are lateralized to one visual hemifield, tracking capacity is drastically reduced relative to bilateral tracking trials. These data suggest that tracking for each hemifield is carried o...
Consider two sequential tasks, one visual, one abstract. In the visual search task, observers examine object after object to find a target. The target is present on only a proportion of the trials, observers search as long as they like and declare finally whether the target is present or absent. They are rewarded for correct responses. In the abstr...
People often fail to report large changes in visual displays (“change blindness”). One influential interpretation is that perceptual representations are not as rich as people think. However, change detection could fail at any of three stages: perception, memory or comparison. We tested the same stimuli at each stage in three experiments.
All experi...
When one object occludes another, occluded objects appear to continue invisibly behind the occluder. Does this “amodal completion” require attention? Hulleman (VSS07) showed that efficient search for vertical bars among horizontal bars was disrupted by occluding diagonal bars. This suggests that the amodal completion that created oriented occluded...
Humans can track 3–5 independently moving objects among identical moving distractors (multiple object tracking). This has been taken as a demonstration of simultaneous parallel attention. Does this distributed attention facilitate letter identification, or do tracking and letter identification employ separate attentional resources?
Eight participan...
Recently, we have reported ERP activity that appears to index both the number of items being maintained in visual working memory (VWM) tasks (Vogel & Machizawa, 2004), and the number of items being tracked during a multiple object tracking (MOT) task (Drew & Vogel, 2008). However, while a similar sustained contralateral negativity is observed for b...
When and why people decide to stop searching for a target that they have not found is an old question. At VSS last year, we demonstrated that payoff matrices can bias observers towards responding that a target is present or absent in visual search. This year, we attempt to explain reaction time and detection rates by considering time-dependent rewa...
Humans can track multiple moving objects. Is this accomplished by attending to all the objects at the same time or do we attend to each object in turn? We addressed this question using a novel application of the classic simultaneous-sequential paradigm. We considered a display in which objects moved for only part of the time. In one condition, the...
Many experiments have investigated visual search for simple stimuli like colored bars or alphanumeric characters. When eye movements are not a limiting factor, these tasks tend to produce roughly linear functions relating reaction time (RT) to the number of items in the display (set size). The slopes of the RT × set size functions for different sea...
Contextual cueing (CC) experiments show that when visual search displays are repeated, reaction times (RTs) to find a target decrease over time even when observers are not aware of the repetition. In other experiments, observers use information about features, like color, to guide attention to likely target locations. Do observers use implicit memo...
In standard visual search paradigms, targets are present on 50% of trials. Many important search tasks (e.g., medical and baggage screening) involve much lower target prevalence. Previously, Wolfe, Horowitz, and Kenner (Nature, 2005) reported that a task yielding 7% miss errors at 50% prevalence produced 30% errors at 1% prevalence. Their task was...
In a visual change detection task, observers search for a change between two displays presented in alternation. When do observers have knowledge about the presence of a change? Does knowledge accumulate gradually, or is the change detected swiftly, but only after the changed region is selected by attention? While several researchers have reported e...
In many socially important search tasks (e.g. medical and baggage screening) targets are rare. Previously, we have demonstrated that miss error rates are 2–3 times higher at low (1–2%) target prevalence than at high (50%) prevalence (Wolfe, Horowitz, & Kenner, Nature, 2005). This prevalence effect is robust and difficult to cure. Last year, we demo...
In search tasks, observers can guide attention to likely targets based on features such as color and orientation. Does guidance develop over time during search or does it act as a fixed filter, present from the start of a trial? We measured the timecourse of guidance by presenting guiding color information prior to the search array. Observers searc...
In visual search tasks, attention can be guided to items that share features (e.g. color) with the desired target. Is feature guidance available immediately from the onset of a stimulus? To address this question, observers reported whether the gap in a target C was on the left or right among distractor Cs with gaps facing up or down. Stimuli were p...
How does the visual system use speed to guide visual search? According to the absolute speed hypothesis, proposed by Ivry and Cohen (1992), the fastest moving object in the environment is the most salient and readily captures attention. This hypothesis is supported by Ivry and Cohen's visual search studies showing that faster-moving targets among s...
In multiple object tracking (MOT) experiments, observers are capable of tracking 3–5 targets among identical distractors. What information about target trajectories can the visual system use in this task? We present a new method, which allows us to measure the precision of observers' information about object motion direction in MOT.
In Exp. 1, we m...
During an extended visual search task (e.g. search for T among Ls, “TvL”), does sensitivity to target identity accumulate gradually or are targets identified swiftly, but only once they are selected by attention? We used a novel, event-related technique that allowed us to measure signal strength at different times prior to the end of search. Os sea...
