Visual search with animal fear-relevant stimuli: A tale of two procedures

The present study assessed preferential attentional processing of animal fear-relevant stimuli in two procedures, Search and Interference tasks, which have been suggested to reflect on attentional capture due to the fear-relevance of the stimuli presented. In the Search task, participants (N = 154) searched fear-relevant (i.e., snakes and spiders) and non fear-relevant (i.e., fish and birds) backgrounds to determine the presence or absence of a deviant animal from the opposite category. In the Interference task, the same participants searched for the presence or absence of a neutral target (a cat) when either a snake, spider or no distracter were embedded amongst backgrounds of other animal stimuli. Replicating previous findings, preferential attentional processing of animal fear-relevant stimuli was evident in both procedures and participants who specifically feared one animal but not the other showed enhanced preferential processing of their feared fear-relevant animal. However, across the entire sample, there was no relationship between self-reported levels of animal fear and preferential processing which may reflect on the fact that substantial preferential attentional processing of fear-relevant animals was evident in the entire sample. Also, preferential attentional processing as assessed in the two tasks was not related. Delayed disengagement from fear-relevant stimuli appeared to underlie performance in the search task but not in the interference task.     

Moray revisited: High-priority affective stimuli and visual search

Previous research offers conflicting suggestions about whether “high-priority” verbal stimuli such as an individual's own name or emotionally charged words automatically grab attention and/or can be detected without the usual capacity limitations. Nine experiments investigated this issue, using visual search through displays of words. In speeded search tasks, the subject's own name was detected more quickly than other targets, but in no case were search slopes flat enough to suggest parallel search or “pop-out”. Further, names were not found to be unusually potent distractors. Emotionally charged words were neither more readily detected as targets nor more potent as distractors than neutral words. Acomparison of observers' accuracy in searching briefly exposed simultaneous vs. successive displays provided further evidence that search for “high-priority” word targets is subject to the same severe capacity limitations as those that are found with search for neutral words.     

The role of priming in conjunctive visual search

To assess the role of priming in conjunctive visual search tasks, we systematically varied the consistency of the target and distractor identity between different conditions. Search was fastest in the standard conjunctive search paradigm where identities remained constant. Search was slowest when potential target identity varied predictably for each successive trial (the 'switch' condition). The role of priming was also demonstrated on a trial-by-trial basis in a 'streak' condition where target and distractor identity was unpredictable yet was consistent within streaks. When the target to be found was the same for a few trials in a row, search performance became similar to that when the potential target was the same on all trials. A similar pattern was found for the target absent trials, suggesting that priming is based on the whole search array rather than just the target in each case. Further analysis indicated that the effects of priming are sufficiently strong to account for the advantage seen for the conjunctive search task. We conclude that the role of priming in visual search is underestimated in current theories of visual search and that differences in search times often attributed to top-down guidance may instead reflect the benefits of priming.     

The role of configuration and target discriminability in a visual search task

Ss sorted through decks of cards bearing five-element patterns, separating those in which all five were identical from those in which one of the five was different from the remaining four. Sorting time depended on the configuration and size of the pattern in which the elements were arranged but was independent of the goodness of these patterns. It was concluded that Ss did not attend to the patterns themselves, but just to the elements comprising them in searching for the discrepant element. The differences owing to the patterns appear to be due in part to the compactness of the configurations.     

The role of space and time in object-based visual search

Recently we have provided evidence that observers more readily select a target from a visual search display if the motion trajectory of the display object suggests that the observer has dealt with it before. Here we test the prediction that this object-based memory effect on search breaks down if the spatiotemporal trajectory is disrupted. Observers searched a display for a target shape among multiple distractors. The entire search display then passed behind an occluder and reemerged in either the same or a different configuration. Experiment 1 shows that the same-object benefit for selection disappears whenever a spatial disruption is involved, but that it may survive a brief temporal disruption. Experiment 2 shows that with sufficiently long gaps, a temporal disruption also destroys the same-object benefit for selective attention. Experiment 3 demonstrates that the same-object effect is even stronger when there only is a very small probability that the target can be found at the same location as before. This also made the task sensitive to brief temporal disruptions. We conclude that a coherent spatiotemporal history of a display object supports the selection of its relevant subregions.     

Respiratory sinus arrhythmia in response to fear-relevant and fear-irrelevant stimuli

Heart period variability and heart rate were studied in 15 women and 15 men while they were viewing negatively (snakes/spiders), neutrally (scenic views), and positively (cats and kittens/puppies and dogs) valenced films. Time-frequency analyses of the heart period variability power spectrum in the high frequency region (0.12-0.4 Hz), reflecting respiratory sinus arrhythmia (RSA), were carried out during 5 minutes in each condition. The main finding showed that RSA-magnitude (high frequency power) was inversely related to emotional valence: lowest magnitudes were found in response to positive films, and highest magnitude to negative films. The findings were interpreted as reflecting motor or behavioral inhibition, and increased attention to negatively valenced, stimuli.     

The role of within-dimension singleton priming in visual search

The authors report a newly identified intertrial priming phenomenon, within-dimension singleton priming, by which search for a target that happens to be a singleton on the current trial is faster when the target on the previous trial had also been a singleton on the same dimension rather than a nonsingleton. This effect was replicated in 6 experiments with different procedures, with singletons on various dimensions, when the featural contrast defining the singleton remained the same or changed within a dimension from one trial to the next, and when the target was a singleton on a target-defining dimension or on an irrelevant dimension. These findings cannot be explained by previously demonstrated intertrial repetition effects such as dimension-specific priming or priming of pop-out. Theoretical implications of the within-dimension singleton priming phenomenon are discussed relative to the dimension-weighting hypothesis, the role of stimulus-driven salience in feature-guided search, and the roles of intertrial priming and goal-directed factors in visual search.     

Attention allocation and habituation to anger-related stimuli during a visual search task

A substantial amount of data has accumulated demonstrating that emotionally disordered subjects are prone to bias their attention toward threatening, emotionally relevant stimuli. Little attention has been reserved for the study of cognitive processes involved in anger arousal. In the present study, we investigated whether mood-congruent attentional biases could be demonstrated in subjects of varying levels of trait anger using a visual search task. This task also assessed whether mood-congruent biases diminished with repeated exposure to specific emotion stimuli. To investigate state-trait interaction effects, a naturalistic, anger-inducing insult was administered to half the subjects. There was a positive relation between participants' level of trait anger and their degree of mood-congruent attentional bias toward anger-related cues only after an insult. As predicted, this effect diminished across blocks of trials. Aggr. Behav. 24:399–409, 1998. © 1998 Wiley-Liss, Inc.     

Inhibitory tagging in visual search can be found if search stimuli remain visible

Klein (1988) reported that inhibitory tagging (i.e., inhibition of return in visual search) made reaction times for the detection of small probes increase at locations where there had previously been rejected items in serial visual search. It is reasonable that the attended and rejected locations are inhibited. However, subsequent studies did not support Klein's idea. In these studies, inhibitory tagging was tested after removing the items from the search tasks. The paradigms in these studies were not appropriate for testing an object-based inhibitory effect because the objects (i.e., items) were removed from the display. In the present study, we found that evidence of inhibitory tagging could be observed only when the items of the search tasks were maintained until the responses for the small probes were made. This appeared to be an object-based effect.     

Using facial emotional stimuli in visual search experiments: The arousal factor explains contradictory results

For more than two decades, visual search experiments using pictures of emotional faces as stimuli have generated contradictory results. Evidence of a superior detection of angry faces compared to happy faces have been mixed with an equal amount of evidence in the opposite direction. In this article, we review this literature, and examine the hypothesis that the neglected stimulus factor of emotional arousal may explain these contradictory results. Through an extensive reanalysis of results from our own laboratory as well as from other researchers, we show that the arousal factor systematically influences the outcome of the reviewed visual search experiments, and may thus provide a key to the historical contradictions within this research field.     

Aging and guided visual search: the role of visual working memory

In the present study, we examined age-related differences in utilizing learned associations to guide visual search. Participants viewed an object cue that was associated with 1 or 2 target colors, followed by a search array. Older adults showed slower RTs, larger visual search slopes, and reduced cue–target association knowledge than did younger adults. We also found increased search RTs and higher error rates when the cue was associated with 2 colors instead of 1. However, visual search slopes did not vary with the number of associated colors. This indicates that participants could activate multiple templates simultaneously to guide the search or retrieve associative information directly from the long-term memory. Furthermore, regression analyses showed that VWMC can predict both visual search performances and cue–target association knowledge. More broadly, our results demonstrate that VWMC can modify the effects of age on cued visual search performance.     

Linguistically mediated visual search: The critical role of speech rate

Recent studies have shown that the presentation of concurrent linguistic context can lead to highly efficient performance in a standard conjunction search task by the induction of an incremental search strategy (Spivey, Tyler, Eberhard, & Tanenhaus, 2001). However, these findings were obtained under anomalously slow speech rate conditions. Accordingly, in the present study, the effects of concurrent linguistic context on visual search performance were compared when speech was recorded at both a normal rate and a slow rate. The findings provided clear evidence that the visual search benefit afforded by concurrent linguistic context was contingent on speech rate, with normal speech producing a smaller benefit. Overall, these findings have important implications for understanding how linguistic and visual processes interact in real time and suggest a disparity in the temporal resolution of speech comprehension and visual search processes.     

The role of visual and body movement information in infant search

Three experiments investigated the use of visual input and body movement input arising from movement through the world on spatial orientation. Infants between 9 1/2 and 18 months participated in a search task in which they searched for a toy hidden in 1 of 2 containers. Prior to beginning search, either the infants or the containers were rotated 180 degrees; these rotations occurred in a lit or dark environment. These experiments were distinguished by the environmental cues for object location; Experiment 1 used a position cue, Experiment 2 a color cue, and Experiment 3 both position and color cues. Accuracy was better in Experiments 2 and 3 than in Experiment 1. All studies found that search was best after infant movement in the light; all other conditions led to equivalently worse performance. These results are discussed relative to a theoretical characterization of spatial coding focusing on the uses of spatial information.     

The role of memory and restricted context in repeated visual search

Previous studies have shown that the efficiency of visual search does not improve when participants search through the same unchanging display for hundreds of trials (repeated search), even though the participants have a clear memory of the search display. In this article, we ask two important questions. First, why do participants not use memory to help search the repeated display? Second, can context be introduced so that participants are able to guide their attention to the relevant repeated items? Experiments 1-4 show that participants choose not to use a memory strategy because, under these conditions, repeated memory search is actually less efficient than repeated visual search, even though the latter task is in itself relatively inefficient. However, when the visual search task is given context, so that only a subset of the items are ever pertinent, participants can learn to restrict their attention to the relevant stimuli (Experiments 5 and 6).     

The role of spatial working memory in visual search efficiency

Many theories have proposed that visual working memory plays an important role in visual search. In contrast, by showing that a nonspatial working memory load did not interfere with search efficiency, Woodman, Vogel, and Luck (2001) recently proposed that the role of working memory in visual search is insignificant. However, the visual search process may interfere with spatial working memory. In the present study, a visual search task was performed concurrently with either a spatial working memory task (Experiment 1) or a nonspatial working memory task (Experiment 2). We found that the visual search process interfered with a spatial working memory load, but not with a nonspatial working memory load. These results suggest that there is a distinction between spatial and nonspatial working memory in terms of interactions with visual search tasks. These results imply that the visual search process and spatial working memory storage require the same limited-capacity mechanisms.     

The role of categorization in visual search for orientation.

Visual search for 1 target orientation is fast and virtually independent of set size if all of the distractors are of a single, different orientation. However, in the presence of distractors of several orientations, search can become inefficient and strongly dependent on set size (Exp. 1). Search can be inefficient even if only 2 distractor orientations are used and even if those orientations are quite remote from the target orientation (e.g. 20 degrees or even 40 degrees away, Exp. 2). Search for 1 orientation among heterogeneous distractor orientations becomes more efficient if the target orientation is the only item possessing a categorical attribute such as steep, shallow (Exp. 3), tilted left or tilted right (Exp. 4), or simply tilted (Exps. 5 and 6). Orientation categories appear to be 1 of several strategies used in visual search for orientation. These serve as a compromise between the limits on parallel visual processing and the demands of a complex visual world.     

The types of stimuli loaded in memory can modulate its effects on visual search

The effects of memory load in visual search (VS) have shown a diversity of results from the absence through beneficial and detrimental effects of a concurrent memory load in VS performance. One of the hypotheses intended to explain the heterogeneity of results follows the idea proposed by certain models in the context of VS that the contents of working memory (WM) can modulate the attentional processes involved in VS (Desimone & Duncan, 1995; Duncan & Humphreys, 1989). In four experiments, we manipulated the similarity of information maintained in WM and those materials playing the role of target and distractors in the VS task. The results showed a beneficial effect in the first two experiments, where the materials in WM matched the target in VS. However, when they matched the distractors in the attentional task there is no effect in the slope of the search function. Present results strengthen those theories supporting that visual working memory is fractionated to allow for maintenance of items not essential to the attentional task (Downing & Dodds, 2004).