No evidence of attentional prioritization for threatening targets in visual search.

Throughout human evolutionary history, snakes have been associated with danger and threat. Research has shown that snakes are prioritized by our attentional system, despite many of us rarely encountering them in our daily lives. We conducted two high-powered, pre-registered experiments (total N = 224) manipulating target prevalence to understand this heightened prioritization of threatening targets. Target prevalence refers to the proportion of trials wherein a target is presented; reductions in prevalence consistently reduce the likelihood that targets will be found. We reasoned that snake targets in visual search should experience weaker effects of low target prevalence compared to non-threatening targets (rabbits) because they should be prioritized by searchers despite appearing rarely. In both experiments, we found evidence of classic prevalence effects but (contrasting prior work) we also found that search for threatening targets was slower and less accurate than for nonthreatening targets. This surprising result is possibly due to methodological issues common in prior studies, including comparatively smaller sample sizes, fewer trials, and a tendency to exclusively examine conditions of relatively high prevalence. Our findings call into question accounts of threat prioritization and suggest that prior attention findings may be constrained to a narrow range of circumstances.

Can the processing of task-irrelevant threatening stimuli be inhibited? - The role of shape and valence in the saliency of threatening objects.

Numerous studies have demonstrated that attention is quickly oriented towards threatening stimuli, and that this attentional bias is difficult to inhibit. The root cause(s) of this bias may be attributable to the affective (e.g., valence) or visual features (e.g., shape) of threats. In two experiments (behavioral, eye-tracking), we tested which features play a bigger role in the salience of threats. In both experiments, participants looked for a neutral target (butterfly, lock) among other neutral objects. In half of the trials a threatening (snake, gun) or nonthreatening (but visually similar; worm, hairdryer) task-irrelevant distractor was also present at a near or far distance from the target. Behavioral results indicate that both distractor types interfered with task performance. Rejecting nonthreatening distractors as nontargets was easier when they were presented further from the target but distance had no effect when the distractor was threatening. Eye-tracking results showed that participants fixated less often (and for less time) on threatening compared to nonthreatening distractors. They also viewed targets for less time when a threatening distractor was present (compared to nonthreatening). Results suggest that visual features of threats are easier to suppress than affective features, and the latter may have a stronger role in eliciting attentional biases.

Just say 'I don't know': Understanding information stagnation during a highly ambiguous visual search task.

Visual search experiments typically involve participants searching simple displays with two potential response options: 'present' or 'absent'. Here we examined search behavior and decision-making when participants were tasked with searching ambiguous displays whilst also being given a third response option: 'I don't know'. Participants searched for a simple target (the letter 'o') amongst other letters in the displays. We made the target difficult to detect by increasing the degree to which letters overlapped in the displays. The results showed that as overlap increased, participants were more likely to respond 'I don't know', as expected. RT analyses demonstrated that 'I don't know' responses occurred at a later time than 'present' responses (but before 'absent' responses) when the overlap was low. By contrast, when the overlap was high, 'I don't know' responses occurred very rapidly. We discuss the implications of our findings for current models and theories in terms of what we refer to as 'information stagnation' during visual search.

How does searching for faces among similar-looking distractors affect distractor memory?

Prior research has shown that searching for multiple targets in a visual search task enhances distractor memory in a subsequent recognition test. Three non-mutually exclusive accounts have been offered to explain this phenomenon. The mental comparison hypothesis states that searching for multiple targets requires participants to make more mental comparisons between the targets and the distractors, which enhances distractor memory. The attention allocation hypothesis states that participants allocate more attention to distractors because a multiple-target search cue leads them to expect a more difficult search. Finally, the partial match hypothesis states that searching for multiple targets increases the amount of featural overlap between targets and distractors, which necessitates greater attention in order to reject each distractor. In two experiments, we examined these hypotheses by manipulating visual working memory (VWM) load and target-distractor similarity of AI-generated faces in a visual search (i.e., RSVP) task. Distractor similarity was manipulated using a multidimensional scaling model constructed from facial landmarks and other metadata of each face. In both experiments, distractors from multiple-target searches were recognized better than distractors from single-target searches. Experiment 2 additionally revealed that increased target-distractor similarity during search improved distractor recognition memory, consistent with the partial match hypothesis.

The Oddity Detection in Diverse Scenes (ODDS) database: Validated real-world scenes for studying anomaly detection.

Many applied screening tasks (e.g., medical image or baggage screening) involve challenging searches for which standard laboratory search is rarely equivalent. For example, whereas laboratory search frequently requires observers to look for precisely defined targets among isolated, non-overlapping images randomly arrayed on clean backgrounds, medical images present unspecified targets in noisy, yet spatially regular scenes. Those unspecified targets are typically oddities, elements that do not belong. To develop a closer laboratory analogue to this, we created a database of scenes containing subtle, ill-specified "oddity" targets. These scenes have similar perceptual densities and spatial regularities to those found in expert search tasks, and each includes 16 variants of the unedited scene wherein an oddity (a subtle deformation of the scene) is hidden. In Experiment 1, eight volunteers searched thousands of scene variants for an oddity. Regardless of their search accuracy, they were then shown the highlighted anomaly and rated its subtlety. Subtlety ratings reliably predicted search performance (accuracy and response times) and did so better than image statistics. In Experiment 2, we conducted a conceptual replication in which a larger group of naïve searchers scanned subsets of the scene variants. Prior subtlety ratings reliably predicted search outcomes. Whereas medical image targets are difficult for naïve searchers to detect, our database contains thousands of interior and exterior scenes that vary in difficulty, but are nevertheless searchable by novices. In this way, the stimuli will be useful for studying visual search as it typically occurs in expert domains: Ill-specified search for anomalies in noisy displays.

Task-irrelevant threatening information is harder to ignore than other valences.

Emotionally salient objects activate the survival circuits of the brain and are given priority in cognitive processing, even at the cost of inhibiting ongoing activities. These circuits arouse and prepare the organism to take swift action when needed. Previous studies have suggested, however, that not all emotional dimensions are equally prioritized. Threatening stimuli may have greater prominence than other emotional categories. Thus, we sought to compare the effects that stimuli of varying emotions would have on orienting and executive attentional processing. We performed two experiments to broaden our understanding of the attentional consequences of threats through the monitoring of participants' eye movements. Participants were exposed to emotionally charged (threatening, nonthreatening negative, positive) and neutral pictures as task-irrelevant distractors while performing a primary visual search task (under conditions of varying cognitive load). Behavioural results showed that participants found the first target number more slowly when the distractor image was threatening, but overall task completion times were actually speeded in this condition (relative to other valences). Further, participants fixated on threatening distractor images earlier and observed them longer than other valences. Results were more pronounced when the primary task was harder. These biases were not evident for positive and nonthreatening images, presumably because participants were able to ignore them, providing further support to the contention that threatening stimuli hold greater prominence than other emotional categories. Together, our results are in line with previous studies suggesting that the processing of threatening stimuli is speeded, potentially because of differences in the brain circuits involved. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Task demands determine whether shape or arousal of a stimulus modulates competition for visual working memory resources.

It has been posited (Öhman, 1986) that the processing of threatening stimuli became prioritized during the course of mammalian evolution and that such objects may still enjoy an advantage in visual processing to this day. It has been well-documented that both mid-level visual features (i.e., conjunctions of low-level features) and the arousal level of threatening stimuli affect attentional allocation (Cisler & Koster, 2010; Wolfe & Horowitz, 2004). Despite this, few studies have investigated the effect these factors have on visual working memory resources. Here, we investigated these factors using a rapid serial visual presentation (RSVP) paradigm, and by manipulating mid-level features (specifically, shape: similar vs. dissimilar) and the arousal level (non-threatening vs threatening) of the stimuli. Participants watched an RSVP stream in preparation for an upcoming memory test. Then, they completed a two-alternative forced-choice recognition memory test (with semantically matched foils) wherein they had to identify which item they had seen in the RSVP stream. Our results showed that when shape was a sufficient feature to discriminate the target from the other items in the stream, there was no effect of arousal (i.e., threat level) on reaction time or accuracy during the memory test. However, when the shapes of all the stimuli in the visual stream were highly similar, an effect of arousal appeared: When the target had a different arousal level than the background items (i.e., non-targets), performance was improved. Together, the results suggest that both mid-level visual features and arousal level can modulate competition for visual working memory resources.

Examining the effects of passive and active strategy use during interactive search for LEGO® bricks.

In many important search tasks, observers must find what they are looking for using only visual information (e.g., X-ray baggage screening/medical screening). However, numerous other search tasks can only be effectively completed when the searcher uses their hands to find what they are looking for (e.g., "rummage" search). Unfortunately, it is not currently well understood how observers conduct such "interactive" searches nor what the best strategies might be for doing so. Here, we first review the limited literature on interactive search. We then present a novel methodology for the study of interactive search that involves having observers seek out LEGO® targets in a cluttered tray of assorted bricks. In our validation task, we confirm the validity of this approach by demonstrating that it produces sensible patterns of diminishing returns in response time as targets are removed from the set as well as hastened search times for larger targets. In our experiment, we modify the approach, refining its systematicity and experimental control. We also build on prior work exploring strategy use in visual search by investigating the extent to which active and passive strategy use impacts performance in interactive search. In contrast to our prior findings in hybrid visual search (Madrid & Hout, 2019), our current findings suggest that in interactive search, an active search strategy can be superior to a passive one. We close by offering a conceptual model (the Interactive Multiple Decision Model [i-MDM]) that explicates the steps involved in a search task of this nature, and we then provide suggestions for how to further refine the task to achieve higher internal validity and to delve deeper into questions of theoretical importance in the field of interactive search. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The effects of task-irrelevant threatening stimuli on orienting- and executive attentional processes under cognitive load.

Human visual attention is biased to rapidly detect threats in the environment so that our nervous system can initiate quick reactions. The processes underlying threat detection (and how they operate under cognitive load), however, are still poorly understood. Thus, we sought to test the impact of task-irrelevant threatening stimuli on the salience network and executive control of attention during low and high cognitive load. Participants were exposed to neutral or threatening pictures (with moderate and high arousal levels) as task-irrelevant distractors in near (parafoveal) and far (peripheral) positions while searching for numbers in ascending order in a matrix array. We measured reaction times and recorded eye-movements. Our results showed that task-irrelevant distractors primarily influenced behavioural measures during high cognitive load. The distracting effect of threatening images with moderate arousal level slowed reaction times for finding the first number. However, this slowing was offset by high arousal threatening stimuli, leading to overall shorter search times. Eye-tracking measures showed that participants fixated threatening pictures more later and for shorter durations compared to neutral images. Together, our results indicate a complex relationship between threats and attention that results not in a unitary bias but in a sequence of effects that unfold over time.

Avoiding potential pitfalls in visual search and eye-movement experiments: A tutorial review.

Examining eye-movement behavior during visual search is an increasingly popular approach for gaining insights into the moment-to-moment processing that takes place when we look for targets in our environment. In this tutorial review, we describe a set of pitfalls and considerations that are important for researchers - both experienced and new to the field - when engaging in eye-movement and visual search experiments. We walk the reader through the research cycle of a visual search and eye-movement experiment, from choosing the right predictions, through to data collection, reporting of methodology, analytic approaches, the different dependent variables to analyze, and drawing conclusions from patterns of results. Overall, our hope is that this review can serve as a guide, a talking point, a reflection on the practices and potential problems with the current literature on this topic, and ultimately a first step towards standardizing research practices in the field.

Eye movements reflect expertise development in hybrid search.

Domain-specific expertise changes the way people perceive, process, and remember information from that domain. This is often observed in visual domains involving skilled searches, such as athletics referees, or professional visual searchers (e.g., security and medical screeners). Although existing research has compared expert to novice performance in visual search, little work has directly documented how accumulating experiences change behavior. A longitudinal approach to studying visual search performance may permit a finer-grained understanding of experience-dependent changes in visual scanning, and the extent to which various cognitive processes are affected by experience. In this study, participants acquired experience by taking part in many experimental sessions over the course of an academic semester. Searchers looked for 20 categories of targets simultaneously (which appeared with unequal frequency), in displays with 0-3 targets present, while having their eye movements recorded. With experience, accuracy increased and response times decreased. Fixation probabilities and durations decreased with increasing experience, but saccade amplitudes and visual span increased. These findings suggest that the behavioral benefits endowed by expertise emerge from oculomotor behaviors that reflect enhanced reliance on memory to guide attention and the ability to process more of the visual field within individual fixations.

Typicality guides attention during categorical search, but not universally so.

The degree to which an item is rated as being a typical member of its category influences an observer's ability to find that item during word-cued search. However, there are conflicting accounts as to whether or not typicality affects attentional guidance to categorical items, or whether it affects some other aspect of the search process. In this study, we employed word-cued search and eye tracking to disentangle typicality effects on attentional guidance and target verification across differing category cue specificities (i.e., superordinate or basic-level cues), while also varying the degree of similarity between targets and non-targets. We found that typicality influenced attentional guidance when searchers were cued at the superordinate level (e.g., clothing). When cues were provided at the basic level (e.g., pants), typicality did not influence attentional guidance, and only affected target verification when there was featural similarity between targets and non-targets. When a searcher uses a target template comprising features cued at the basic level, therefore, target/non-target similarity produces interference that affects attentional guidance, but we did not find evidence that it also affects target verification.

The detail is in the difficulty: Challenging search facilitates rich incidental object encoding.

When searching for objects in the environment, observers necessarily encounter other, nontarget, objects. Despite their irrelevance for search, observers often incidentally encode the details of these objects, an effect that is exaggerated as the search task becomes more challenging. Although it is well established that searchers create incidental memories for targets, less is known about the fidelity with which nontargets are remembered. Do observers store richly detailed representations of nontargets, or are these memories characterized by gist-level detail, containing only the information necessary to reject the item as a nontarget? We addressed this question across two experiments in which observers completed multiple-target (one to four potential targets) searches, followed by surprise alternative forced-choice (AFC) recognition tests for all encountered objects. To assess the detail of incidentally stored memories, we used similarity rankings derived from multidimensional scaling to manipulate the perceptual similarity across objects in 4-AFC (Experiment 1a) and 16-AFC (Experiments 1b and 2) tests. Replicating prior work, observers recognized more nontarget objects encountered during challenging, relative to easier, searches. More importantly, AFC results revealed that observers stored more than gist-level detail: When search objects were not recognized, observers systematically chose lures with higher perceptual similarity, reflecting partial encoding of the search object's perceptual features. Further, similarity effects increased with search difficulty, revealing that incidental memories for visual search objects are sharpened when the search task requires greater attentional processing.

Examining the Role of Eye Movements During Conversational Listening in Noise.

Speech comprehension is often thought of as an entirely auditory process, but both normal hearing and hearing-impaired individuals sometimes use visual attention to disambiguate speech, particularly when it is difficult to hear. Many studies have investigated how visual attention (or the lack thereof) impacts the perception of simple speech sounds such as isolated consonants, but there is a gap in the literature concerning visual attention during natural speech comprehension. This issue needs to be addressed, as individuals process sounds and words in everyday speech differently than when they are separated into individual elements with no competing sound sources or noise. Moreover, further research is needed to explore patterns of eye movements during speech comprehension - especially in the presence of noise - as such an investigation would allow us to better understand how people strategically use visual information while processing speech. To this end, we conducted an experiment to track eye-gaze behavior during a series of listening tasks as a function of the number of speakers, background noise intensity, and the presence or absence of simulated hearing impairment. Our specific aims were to discover how individuals might adapt their oculomotor behavior to compensate for the difficulty of the listening scenario, such as when listening in noisy environments or experiencing simulated hearing loss. Speech comprehension difficulty was manipulated by simulating hearing loss and varying background noise intensity. Results showed that eye movements were affected by the number of speakers, simulated hearing impairment, and the presence of noise. Further, findings showed that differing levels of signal-to-noise ratio (SNR) led to changes in eye-gaze behavior. Most notably, we found that the addition of visual information (i.e. videos vs. auditory information only) led to enhanced speech comprehension - highlighting the strategic usage of visual information during this process.

The confirmation and prevalence biases in visual search reflect separate underlying processes.

Research by Rajsic, Wilson, and Pratt (2015, 2017) suggests that people are biased to use a target-confirming strategy when performing simple visual search. In 3 experiments, we sought to determine whether another stubborn phenomenon in visual search, the low-prevalence effect (Wolfe, Horowitz, & Kenner, 2005), would modulate this confirmatory bias. We varied the reliability of the initial cue: For some people, targets usually occurred in the cued color (high prevalence). For others, targets rarely matched the cues (low prevalence). High cue-target prevalence exacerbated the confirmation bias, indexed via search response times (RTs) and eye-tracking measures. Surprisingly, given low cue-target prevalence, people remained biased to examine cue-colored letters, even though cue-colored targets were exceedingly rare. At the same time, people were more fluent at detecting the more common, cue-mismatching targets. The findings suggest that attention is guided to "confirm" the more available cued target template, but prevalence learning over time determines how fluently objects are perceptually appreciated. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

The spatial arrangement method of measuring similarity can capture high-dimensional semantic structures.

Psychologists collect similarity data to study a variety of phenomena including categorization, generalization and discrimination, and representation itself. However, collecting similarity judgments between all pairs of items in a set is expensive, spurring development of techniques like the Spatial Arrangement Method (SpAM; Goldstone, Behavior Research Methods, Instruments, & Computers, 26, 381-386, 1994), wherein participants place items on a two-dimensional plane such that proximity reflects perceived similarity. While SpAM greatly hastens similarity measurement, and has been successfully used for lower-dimensional, perceptual stimuli, its suitability for higher-dimensional, conceptual stimuli is less understood. In study 1, we evaluated the ability of SpAM to capture the semantic structure of eight different categories composed of 20-30 words each. First, SpAM distances correlated strongly (r = .71) with pairwise similarity judgments, although below SpAM and pairwise judgment split-half reliabilities (r's > .9). Second, a cross-validation exercise with multidimensional scaling fits at increasing latent dimensionalities suggested that aggregated SpAM data favored higher (> 2) dimensional solutions for seven of the eight categories explored here. Third, split-half reliability of SpAM dissimilarities was high (Pearson r = .90), while the average correlation between pairs of participants was low (r = .15), suggesting that when different participants focus on different pairs of stimulus dimensions, reliable high-dimensional aggregate similarity data is recoverable. In study 2, we show that SpAM can recover the Big Five factor space of personality trait adjectives, and that cross-validation favors a four- or five-dimension solution on this dataset. We conclude that SpAM is an accurate and reliable method of measuring similarity for high-dimensional items like words. We publicly release our data for researchers.

Scene priming provides clues about target appearance that improve attentional guidance during categorical search.

During categorical search (e.g., "look for a dog"), observers have broad information about their intended target, but no specific details about the target's precise appearance. Research suggests that mental representations used to guide attention during categorical search (or search templates) comprise typical or category consistent features. Unlike laboratory settings, real world search is not conducted in isolation; yet to be understood is how context shapes categorical search templates. Here, participants searched for category items after viewing a contextual scene prime. Response times were consistently faster to context-congruent targets, even though searchers had no incentive to intentionally use the scene to shape their template. Eye movements revealed enhanced attentional guidance during congruent searches, suggesting that context allows searchers to develop more useful templates. Thus, contextual primes may trigger scene-specific schemas that activate object features in memory that can then be used to guide attention. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

An algorithm to minimize the number of blocks in incomplete block designs.

Incomplete block designs are experimental designs in which a subset of treatments are included in each block. The researcher must decide which conditions are assigned to each block. This design concept is quite general. At the level of the experiment, a treatment is a condition in an experiment, blocks are different groups of subjects, and the researcher must decide how to assign a subset of conditions to each block of subjects. At the level of the subject, the treatments correspond to individual stimuli, blocks correspond to experimental trials, and the researcher must decide which subset of stimuli to include in each trial. In this article, we present an efficient algorithm that assigns treatments to blocks in an incomplete block design according to two criteria: Each pair of treatments must appear together in at least one block, and the number of blocks in the experiment is minimized. We discuss details and applications of the algorithm and provide software and a web application to generate designs according to the needs of the researcher.

Self-controlled amount and pacing of practice facilitate learning of a sequential timing task.

Allowing learners to control the number of practice trials has been shown to facilitate motor learning (Lessa & Chiviacowsky, 2015; Post et al., 2011; 2014). However, it is uncertain the extent to which prior findings were influenced by the combined effects of allowing participants to control both the pacing- and amount-of-practice. The present study examined the independent effects of self-controlled amount- and pacing-of-practice on learning a sequential timing task. Participants were assigned to a self-controlled-amount-of-practice (SCA), self-controlled-pacing-of-practice (SCP), yoked-amount-of-practice (YKA), or a yoked-pacing-of-practice (YKP) group. Participants completed acquisition, immediate retention/transfer and delayed retention/transfer. During acquisition, SCA controlled the number of acquisition blocks completed with a fixed inter-trial interval while SCP controlled the inter-trial interval with a fixed number of blocks. Yoked groups were matched to a self-control counterpart so the amount (YKA) and pacing (YKP) were equivalent. Self-control groups demonstrated lower absolute constant error during immediate-retention and lower absolute constant error and variable error during delayed retention (p < .05). For intrinsic motivation, SCA scored significantly higher than SCP for the subscale Interest/Enjoyment (p < .05). Findings indicated that self-control, regardless of type, facilitated motor learning. Further work is needed to continue to examine the relationship between controlling the amount and pacing of practice on skill acquisition.

Examining the effects of passive and active strategies on behavior during hybrid visual memory search: evidence from eye tracking.

Hybrid search requires observers to search both through a visual display and through the contents of memory in order to find designated target items. Because professional hybrid searchers such as airport baggage screeners are required to look for many items simultaneously, it is important to explore any potential strategies that may beneficially impact performance during these societally important tasks. The aim of the current study was to investigate the role that cognitive strategies play in facilitating hybrid search. We hypothesized that observers in a hybrid search task would naturally adopt a strategy in which they remained somewhat passive, allowing targets to "pop out." Alternatively, we considered the possibility that observers could adopt a strategy in which they more actively directed their attention around the visual display. In experiment 1, we compared behavioral responses during uninstructed, passive, and active hybrid search. We found that uninstructed search tended to be more active in nature, but that adopting a passive strategy led to above average performance as indicated by a combined measure of speed and accuracy called a balanced integration score (BIS). We replicated these findings in experiment 2. Additionally, we found that oculomotor behavior in passive hybrid search was characterized by longer saccades, improved attentional guidance, and an improved ability to identify items as targets or distractors (relative to active hybrid search). These results have implications for understanding hybrid visual search and the effect that strategy use has on performance and oculomotor behavior during this common, and at times societally important, task.