Attentional biases in social anxiety: an investigation using the inattentional blindness paradigm

One line of research has examined attentional bias as a potential maintenance factor in social anxiety using cognitive experiment paradigms. The present study sought to examine the utility of the inattentional blindness (IB) paradigm for assessing attentional bias in social anxiety. Unlike other existing paradigms such as the emotional Stroop or dot-probe tasks, the IB paradigm has the advantage of eliminating the individual's expectation and intention to search for social cues, which would reduce strategic or effortful responses. Two independent experiments were conducted using college students scoring high or low on the Fear of Negative Evaluation Scale. In both Experiments 1 and 2, participants were randomized to one of three IB experiment conditions, in which a positive face, a negative face, or a neutral item was unexpectedly presented, in the presence/absence of a bogus-speech threat. The overall pattern of our data suggests the presence of hypervigilant attentional processing in social anxiety. The IB paradigm appears to be a useful addition to existing experiment paradigms for investigating attentional bias in social anxiety and perhaps other psychopathology.     

Working memory and inattentional blindness

Individual differences in working memory predict many aspects of cognitive performance, especially for tasks that demand focused attention. One negative consequence of focused attention is inattentional blindness, the failure to notice unexpected objects when attention is engaged elsewhere. Yet, the relationship between individual differences in working memory and inattentional blindness is unclear; some studies have found that higher working memory capacity is associated with greater noticing, but others have found no direct association. Given the theoretical and practical significance of such individual differences, more definitive tests are needed. In two studies with large samples, we tested the relationship between multiple working memory measures and inattentional blindness. Individual differences in working memory predicted the ability to perform an attention-demanding tracking task, but did not predict the likelihood of noticing an unexpected object present during the task. We discuss the reasons why we might not expect such individual differences in noticing and why other studies may have found them.     

Attending to music decreases inattentional blindness

This article investigates how auditory attention affects inattentional blindness (IB), a failure of conscious awareness in which an observer does not notice an unexpected event because their attention is engaged elsewhere. Previous research using the attentional blink paradigm has indicated that listening to music can reduce failures of conscious awareness. It was proposed that listening to music would decrease IB by reducing observers’ frequency of task-unrelated thoughts (TUTs). Observers completed an IB task that varied both visual and auditory demands. Listening to music was associated with significantly lower IB, but only when observers actively attended to the music. Follow-up experiments suggest this was due to the distracting qualities of the audio task. The results also suggest a complex relationship between IB and TUTs: during demanding tasks, as predicted, noticers of the unexpected stimulus reported fewer TUTs than non-noticers. During less demanding tasks, however, noticers reported more TUTs than non-noticers.     

The attentional cost of inattentional blindness

When our attention is engaged in a visual task, we can be blind to events which would otherwise not be missed. In three experiments, 97 out of the 165 observers performing a visual attention task failed to notice an unexpected, irrelevant object moving across the display. Surprisingly, this object significantly lowered accuracy in the primary task when, and only when, it failed to reach awareness. We suggest that an unexpected stimulus causes a state of alert that would normally generate an attentional shift; if this response is prevented by an attention-consuming task, a portion of the attentional resources remains allocated to the object. Such a portion is large enough to disturb performance, but not so large that the object can be recognized as task-irrelevant and accordingly ignored. Our findings have one counterintuitive implication: irrelevant stimuli might hamper some types of performance only when perceived subliminally.     

Auditory attention causes visual inattentional blindness

When engaged in a visual task, we can fail to detect unexpected events that would otherwise be very noticeable. Here we ask whether a common auditory task, such as that of attending to a verbal stream, can also make us blind to the presence of visual objects that we do not anticipate. In two experiments, one hundred and twenty observers watched a dynamic display while performing either a visual or an auditory attention task, or both simultaneously. When observers were listening to verbal material, in order to either understand it or to remember it (auditory task), their probability of detecting an unexpected visual object was no higher than when they were counting bounces of moving items (visual task), although in the former case the observers' eyes and attention could move around the display freely rather than remaining focused on tracked items. Previous research has shown that attending to verbal material does not affect responses to lights flashing at irregular intervals, suggesting that driving performance is not hampered by listening. The lights, however, were expected. Our data imply that listening to the radio while driving, or to a portable audio player while walking or biking, can impair our reactions to objects or events that we do not expect.     

The neural substrates associated with inattentional blindness

Inattentional blindness is the failure to perceive salient stimuli presented at unattended locations. Whereas the behavioral manifestation of inattentional blindness has been investigated, the neural basis of this phenomenon has remained elusive. In the current study, event-related fMRI was used to identify the neural substrates associated with inattentional blindness. During central fixation, participants named colored digits presented at a peripheral location. On a subset of trials, an unexpected checkerboard circle (the critical stimulus) was presented at the same eccentricity along with the colored digits (a post-scan questionnaire assessed participants’ awareness of the critical stimulus). Neural activity during inattentional blindness was observed in the prefrontal cortex. Together with previous findings, these results call into question the widespread view that activity in the prefrontal cortex reflects conscious processing.     

Individual differences in susceptibility to inattentional blindness

Inattentional blindness refers to the finding that people do not always see what appears in their gaze. Though inattentional blindness affects large percentages of people, it is unclear if there are individual differences in susceptibility. The present study addressed whether individual differences in attentional control, as reflected by variability in working memory capacity, modulate susceptibility to inattentional blindness. Participants watched a classic inattentional blindness video (Simons & Chabris, 1999) and were instructed to count passes among basketball players, wherein 58% noticed the unexpected: a person wearing a gorilla suit. When participants were accurate with their pass counts, individuals with higher working memory capacity were more likely to report seeing the gorilla (67%) than those with lesser working memory capacity (36%). These results suggest that variability in attentional control is a potential mechanism underlying the apparent modulation of inattentional blindness across individuals.     

Executive working memory load induces inattentional blindness

When attention is engaged in a task, unexpected events in the visual scene may go undetected, a phenomenon known as inattentional blindness (IB). At what stage of information processing must attention be engaged for IB to occur? Although manipulations that tax visuospatial attention can induce IB, the evidence is more equivocal for tasks that engage attention at late, central stages of information processing. Here, we tested whether IB can be specifically induced by central executive processes. An unexpected visual stimulus was presented during the retention interval of a working memory task that involved either simply maintaining verbal material or rearranging the material into alphabetical order. The unexpected stimulus was more likely to be missed during manipulation than during simple maintenance of the verbal information. Thus, the engagement of executive processes impairs the ability to detect unexpected, task-irrelevant stimuli, suggesting that IB can result from central, amodal stages of processing.     

Manipulating inattentional blindness within and across sensory modalities

People often fail to consciously perceive visual events that are outside the focus of attention, a phenomenon referred to as inattentional blindness or IB (i.e., Mack & Rock, 1998). Here, we investigated IB for words within and across sensory modalities (visually and auditorily) in order to assess whether dividing attention across different senses has the same consequences as dividing attention within an individual sensory modality. Participants were asked to monitor a rapid stream of pictures or sounds presented concurrently with task-irrelevant words (spoken or written). A word recognition test was used to measure the processing for unattended words compared to word recognition levels after explicitly monitoring the word stream. We were able to produce high levels of IB for visually and auditorily presented words under unimodal conditions (Experiment 1) as well as under crossmodal conditions (Experiment 2). A further manipulation revealed, however, that IB is less prevalent when attention is divided across modalities than within the same modality (Experiment 3). These findings are explained in terms of the attentional load hypothesis and suggest that, contrary to some claims, attention resources are to a certain extent shared across sensory modalities.     

The role of perceptual load in inattentional blindness

Perceptual load theory offers a resolution to the long-standing early vs. late selection debate over whether task-irrelevant stimuli are perceived, suggesting that irrelevant perception depends upon the perceptual load of task-relevant processing. However, previous evidence for this theory has relied on RTs and neuroimaging. Here we tested the effects of load on conscious perception using the "inattentional blindness" paradigm. As predicted by load theory, awareness of a task-irrelevant stimulus was significantly reduced by higher perceptual load (with increased numbers of search items, or a harder discrimination vs. detection task). These results demonstrate that conscious perception of task-irrelevant stimuli critically depends upon the level of task-relevant perceptual load rather than intentions or expectations, thus enhancing the resolution to the early vs. late selection debate offered by the perceptual load theory.     

The gap between inattentional blindness and attentional misdirection

Kuhn and colleagues described a novel attentional misdirection approach (deliberate diversion of attention away from a visually salient stimulus) to investigate overt and covert attention mechanisms in connection with inattentional blindness (not being able to perceive something that is plainly visible because one’s attention has not been focused on it). This misdirection paradigm is valuable to study the temporal relationship between eye movements and visual awareness. Although, as put forth in this comment, the link between attentional misdirection and inattentional blindness needs to be developed further. There are at least four differences between the two paradigms which concern the conceptual aspects of the unexpected object and the methodological aspects of the task design. This highlights the need for a broader theoretical framework incorporating inattentional blindness and overt and covert attention mechanisms. Two possible research lines focusing on the orienting attention research and the “selection-for-action” paradigm are discussed.     

Predicting and manipulating the incidence of inattentional blindness

Inattentional blindness (IB) occurs when an observer, who is engaged in a resource-consuming task, fails to notice an unexpected although salient stimulus appearing in their visual field. The incidence of IB is affected by changes in stimulus-driven properties, but little research has examined individual differences in IB propensity. We examine working memory capacity (WMC), processing styles (flicker task), inhibition (Stroop task), and training in predicting IB. WMC is associated with IB (Experiments 1 and 2) but neither processing style (Experiment 1) nor inhibition (Experiment 2) was associated. In Experiment 2, prior training on a task reduced the incidence of IB compared to no prior training, and this effect was significantly larger when trained on the same tracking task as that used in the IB task rather than a different task. We conclude that IB is related to WMC and that training can influence the incidence of IB.     

Animacy,perceptual load,and inattentional blindness

Inattentional blindness is the failure to notice unexpected objects in a visual scene while engaging in an attention-demanding task. We examined the effects of animacy and perceptual load on inattentional blindness. Participants searched for a category exemplar under low or high perceptual load. On the last trial, the participants were exposed to an unexpected object that was either animate or inanimate. Unexpected objects were detected more frequently when they were animate rather than inanimate, and more frequently with low than with high perceptual loads. We also measured working memory capacity and found that it predicted the detection of unexpected objects, but only with high perceptual loads. The results are consistent with the animate-monitoring hypothesis, which suggests that animate objects capture attention because of the importance of the detection of animate objects in ancestral hunter–gatherer environments.     

Manipulating inattentional blindness within and across sensory modalities

People often fail to consciously perceive visual events that are outside the focus of attention, a phenomenon referred to as inattentional blindness or IB (i.e., Mack & Rock, 1998 Mack, A. and Rock, I. 1998. Inattentional blindness, Cambridge, MA: MIT Press. [Crossref] , [Google Scholar]). Here, we investigated IB for words within and across sensory modalities (visually and auditorily) in order to assess whether dividing attention across different senses has the same consequences as dividing attention within an individual sensory modality. Participants were asked to monitor a rapid stream of pictures or sounds presented concurrently with task-irrelevant words (spoken or written). A word recognition test was used to measure the processing for unattended words compared to word recognition levels after explicitly monitoring the word stream. We were able to produce high levels of IB for visually and auditorily presented words under unimodal conditions (Experiment 1) as well as under crossmodal conditions (Experiment 2). A further manipulation revealed, however, that IB is less prevalent when attention is divided across modalities than within the same modality (Experiment 3). These findings are explained in terms of the attentional load hypothesis and suggest that, contrary to some claims, attention resources are to a certain extent shared across sensory modalities.     

The role of unattended distractors in sustained inattentional blindness

When participants are attending to a subset of visual targets or events and ignoring irrelevant distractors (“selective looking”), they often fail to detect the appearance of an unexpected visual object or event even when the object is visible for several seconds (“sustained inattentional blindness”). An important factor influencing detection rates in selective looking is the attentional set of the participant: the more similar the features of the unexpected object are to the attended ones, the more probably it will be detected. We examined the possible contribution of active ignoring to this similarity effect by studying the role of the distractor objects in sustained inattentional blindness. First we showed the similarity effect for chromatic colors and then we manipulated the similarity of the unexpected object in relation to the distractor objects and did not find any effects. Moreover, we found that inattentional blindness was present even when the displays did not contain any irrelevant to-be-ignored objects. We conclude that attending to target items on the basis of attentional set, but not active ignoring of nontargets items, is sufficient for the occurrence of sustained inattentional blindness.     

Aging increases inattentional blindness to the gorilla in our midst

When engaged in an attention-demanding task, people are surprisingly vulnerable to inattentional blindness--the failure to notice an unexpected event. Two theories of cognitive aging, attentional capacity models and inhibitory deficit models, make opposite predictions about age differences in susceptibility to inattentional blindness. We tested these predictions using an inattentional blindness paradigm developed by Simons and Chabris (1999) and found that older adults were more likely to experience inattentional blindness than young adults. These results are compatible with attentional capacity models of cognitive aging but not with current inhibitory deficit models.     

The effects of individual differences and task difficulty on inattentional blindness

Most studies of inattentional blindness—the failure to notice an unexpected object when attention is focused elsewhere—have focused on one critical trial. For that trial, noticing the unexpected object might be a result of random variability, so that any given individual would be equally likely to notice the unexpected object. On the other hand, individual differences in the ability to perform the primary task might make noticing more likely for some individuals than for others. Increasing the difficulty of the primary task has been shown to decrease noticing rates for both brief static displays (Cartwright-Finch & Lavie, 2007) and dynamic monitoring tasks (Simons & Chabris, 1999). However, those studies did not explore whether individual differences in noticing arise from differences in the ability to perform the primary task. For our Experiment 1, we used a staircase procedure to equate primary task performance across individuals in a dynamic inattentional blindness task and found that the demands of the primary task affected noticing rates when individual differences in accuracy were minimized. In Experiment 2, we found that individual differences in primary task performance did not predict noticing of an unexpected object. Together, these findings suggest that although the demands of the primary task do affect inattentional blindness rates, individual differences in the ability to meet those demands do not.     

Visual short-term memory load suppresses temporo-parietal junction activity and induces inattentional blindness

The right temporo-parietal junction (TPJ) is critical for stimulus-driven attention and visual awareness. Here we show that as the visual short-term memory (VSTM) load of a task increases, activity in this region is increasingly suppressed. Correspondingly, increasing VSTM load impairs the ability of subjects to consciously detect the presence of a novel, unexpected object in the visual field. These results not only demonstrate that VSTM load suppresses TPJ activity and induces inattentional blindness, but also offer a plausible neural mechanism for this perceptual deficit: suppression of the stimulus-driven attentional network.     

Dissociation of processing time and awareness by the inattentional blindness paradigm

Consciousness researchers are interested in distinguishing between mental activity that occurs with and without awareness (i.e., explicit versus implicit processes). The inattentional blindness (IB) paradigm is an excellent tool for this question because it permits the independent manipulation of processing time and awareness. In the present study, we show that implicit texture segregation can occur during inattentional blindness, provided that the texture is exposed for a sufficient duration. In contrast, a Simon effect does not occur during inattentional blindness, even with similar exposure duration of the critical stimulus. This reveals a dissociation between processing time and awareness, consistent with the possibility of separate processing streams for explicit and implicit visual perception.