EXPRESS: The role of perceptual and cognitive load on inattentional blindness: a systematic review and three meta-analyses

The inattentional blindness phenomenon refers to situations where a visible but unexpected stimulus remains consciously unnoticed by observers. This phenomenon is classically explained as the consequence of insufficient attention, because attentional resources are already engaged elsewhere or vary between individuals. However, this attentional-resources view is broad and often imprecise regarding the variety of attentional models, the different pools of resources that can be involved in attentional tasks and the heterogeneity of the experimental paradigms. Our aim was to investigate whether a classic theoretical model of attention, namely the Load Theory, could account for a large range of empirical findings in this field by distinguishing the role of perceptual and cognitive resources in attentional selection and attentional capture by irrelevant stimuli. Since this model has been mostly built on implicit measures of distractor interference, it is unclear whether its predictions also hold when explicit and subjective awareness of an unexpected stimulus is concerned. Therefore, we conducted a systematic review and meta-analyses of inattentional blindness studies investigating the role of perceptual and/or cognitive resources. The results reveal that, in line with the perceptual account of the Load Theory, inattentional blindness significantly increases with the perceptual load of the task. However, the cognitive account of this theory is not clearly supported by the empirical findings analyzed here. Furthermore, the interaction between perceptual and cognitive load on inattentional blindness remains understudied. Theoretical implications for the Load Theory are discussed, notably regarding the difference between attentional capture and subjective awareness paradigms, and further research directions are provided.

Don’t blink: inattentional blindness in radiology report interpretation

Objectives: Medical errors attributable to inattentional blindness (IAB) may contribute to adverse patient outcomes. IAB has not been studied in the context of reviewing written radiological reports. This cross-sectional, deception-controlled study measures IAB of physicians towards an unexpected stimulus while interpreting written radiological reports. Methods: Physicians and residents from multiple fields were asked to interpret four radiology text reports. Embedded in one was an unexpected stimulus (either an abnormally placed medical exam finding or a non-medical quote from the popular television show Doctor Who). Primary outcomes were differences in detection rates for the two stimuli. Secondary outcomes were differences in detection rates based on level of training and specialty. Results: The unexpected stimulus was detected by 47.8% (n = 43) of participants; the non-medical stimulus was detected more often than the medical stimulus (75.0% vs 21.7%, OR 10.8, 95% CI 4.1–28.7; p < 0.0001,). No differences in outcomes were observed between training levels or specialties. Conclusion: Only a minority of physicians successfully detected an unexpected stimulus while interpreting written radiological reports. They were more likely to detect an abnormal non-medical stimulus than a medical stimulus. Findings were independent of the level of training or field of medical practice. Advances in knowledge: This study is the first to show that IAB is indeed present among internal medicine, family medicine, and emergency medicine providers when interpreting written radiology reports.

Horses show individual level lateralisation when inspecting an unfamiliar and unexpected stimulus

Animals must attend to a diverse array of stimuli in their environments. The emotional valence and salience of a stimulus can affect how this information is processed in the brain. Many species preferentially attend to negatively valent stimuli using the sensory organs on the left side of their body and hence the right hemisphere of their brain. Here, we investigated the lateralisation of visual attention to the rapid appearance of a stimulus (an inflated balloon) designed to induce an avoidance reaction and a negatively valent emotional state in 77 Italian saddle horses. Horses’ eyes are laterally positioned on the head, and each eye projects primarily to the contralateral hemisphere, allowing eye use to be a proxy for preferential processing in one hemisphere of the brain. We predicted that horses would inspect the novel and unexpected stimulus with their left eye and hence right hemisphere. We found that horses primarily inspected the balloon with one eye, and most horses had a preferred eye to do so, however, we did not find a population level tendency for this to be the left or the right eye. The strength of this preference tended to decrease over time, with the horses using their non-preferred eye to inspect the balloon increasingly as the trial progressed. Our results confirm a lateralised eye use tendency when viewing negatively emotionally valent stimuli in horses, in agreement with previous findings. However, there was not any alignment of lateralisation at the group level in our sample, suggesting that the expression of lateralisation in horses depends on the sample population and testing context.

PRIMING EFFECTS FOR THE UNEXPECTED STIMULUS IN INATTENTIONAL BLINDNESS

Studies on inattentional blindness demonstrate that a stimulus that unexpectedly appears in the visual environment may be undetected when attention is engaged in a task. The stimulus can still be processed and remembered at the perceptual and semantic level. The question of whether this is still the case when there are items to be ignored in the visual environment remains. In the present study investigating this question, participants attended to furniture pictures while they ignored other pictures. In the inattention trial, an unexpected word appeared in the middle of the circular display. Participants blind to the word were compared to ones who were not exposed to the word. In Experiment 1, participants were more likely to complete a word fragment with this word than the ones who were not exposed to the word. In Experiment 2, participants were more likely to choose the picture of this word than the ones who were not exposed to the word. These studies show that the undetected unexpected stimulus is processed at the perceptual and semantic level and produces priming effects on a subsequent task. Findings were discussed with regards to the possible memory correlates of undetected visual information and levels of consciousness. Keywords: inattentional blindness, priming, consciousness, perceptual processing, semantic processing

Scene and Object Violations Cause Subjective Time Dilation

For a given physical duration, certain events can be experienced as subjectively longer than others, an illusion referred to as subjective time dilation. Many factors have been shown to lead to this illusion in perceived duration, including low-level visual properties of the stimulus (e.g., increase in motion, brightness, and flicker), an unexpected stimulus in a sequence of events, as well as affective factors. Here we report the results of two experiments in which we tested for the influence of scene and object knowledge on subjective time dilation. Based on the results of earlier studies, we predicted that visual scenes and objects containing semantic violations would be judged as lasting longer than control stimuli. The findings from both experiments indicate that stimuli containing semantic violations were judged to be present for longer than stimuli without semantic violations. We interpret our results to mean that neural processes that encode for perception of duration can operate on conceptually integrated scene and object representations. We further conjecture that the underlying neural code for duration perception is likely correlated with the amplitude of neural activity expended on the processing of incoming sensory information.

Serotonergic control in initiating defensive responses to unexpected tactile stimuli in the trap-jaw ant Odontomachus kuroiwae

ABSTRACTThe decision to express either a defensive response or an escape response to a potential threat is crucial for insects to survive. This study investigated an aminergic mechanism underlying defensive responses to unexpected touch in an ant that has powerful mandibles, the so-called trap-jaw. The mandibles close extremely quickly and are used as a weapon during hunting. Tactile stimulation to the abdomen elicited quick forward movements in a dart escape in 90% of the ants in a colony. Less than 10% of the ants responded with a quick defensive turn towards the source of stimulation. To reveal the neuronal mechanisms underlying this defensive behavior, the effect of brain biogenic amines on the responses to tactile stimuli were investigated. The levels of octopamine (OA), dopamine (DA) and serotonin (5HT) in the brain were significantly elevated in ants that responded with a defensive turn to the unexpected stimulus compared with ants that responded with a dart escape. Oral administration of DA and 5HT demonstrated that both amines contributed to the initiation of a defensive response. Oral administration of l-DOPA weakly affected the initiation of the defensive turn, while 5-hydroxy-l-tryptophan (5HTP) strongly affected the initiation of defensive behavior. Oral administration of ketanserin, a 5HT antagonist, inhibited the initiation of the defensive turn in aggressive workers, abolishing the effects of both 5HT and 5HTP on the initiation of turn responses. These results indicate that 5HTergic control in the nervous system is a key for the initiation of defensive behavior in the trap-jaw ant.

Serotonergic control in initiating defensive responses to unexpected tactile stimuli in the trap-jaw ant Odontomachus kuroiwae

ABSTRACTA decision to express a defensive response or an escape response to a potential threat is crucial for insects to survive. This study investigated an aminergic mechanism underlying defensive responses to unexpected touch in an ant that has powerful mandibles, the so-called trap-jaw. The mandibles close extremely quickly and are used as a weapon during hunting. Tactile stimulation to the abdomen elicited quick forward movements in a “dart escape” in 90% of the ants in a colony. Less than 10% of the ants responded with a quick “defensive turn” towards the source of stimulation. To reveal the neuronal control mechanisms underlying this defensive behavior, the effects of brain biogenic amines on the responses to tactile stimulus were investigated. The levels of octopamine (OA), dopamine (DA) and serotonin (5HT) in the brain were significantly elevated in ants that responded with a defensive turn to the unexpected stimulus compared to ants that responded with a dart escape. Oral administration of DA and 5HT demonstrated that both amines contributed to the initiation of a defensive response to the stimulus. Oral administration of L-DOPA weakly affected the initiation of the defensive turn, while 5HTP strongly affected the initiation of defensive behavior. Oral administration of an antagonist of 5HT, ketanserin, abolished the effect of 5HTP. These results indicate that endogenous 5HT in the brain has a key role to play in modulating the initiation of defensive behavior in the trap-jaw ant.

Influence of Pairing Startling Acoustic Stimuli with Postural Responses Induced by Light Touch Displacement

The first exposure to an unexpected, rapid displacement of a light touch reference induces a balance reaction in naïve participants, whereas an arm-tracking behaviour emerges with subsequent exposures. The sudden behaviour change suggests the first trial balance reaction arises from the startling nature of the unexpected stimulus. We investigated how touch-induced balance reactions interact with startling acoustic stimuli. Responses to light touch displacements were tested in 48 participants across six distinct combinations of touch displacement (DISPLACEMENT), acoustic startle (STARTLE), or combined (COMBINED) stimuli. The effect of COMBINED depended, in part, on the history of the preceding stimuli. Participants who received 10 DISPLACEMENT initially, produced facilitated arm-tracking responses with subsequent COMBINED. Participants who received 10 COMBINED initially, produced facilitated balance reactions, with arm-tracking failing to emerge until the acoustic stimuli were discontinued. Participants who received five DISPLACEMENT, after initially habituating to 10 STARTLE, demonstrated re-emergence of the balance reaction with the subsequent COMBINED. Responses evoked by light touch displacements are influenced by the startling nature of the stimulus, suggesting that the selection of a balance reaction to a threatening stimulus is labile and dependent, in part, on the context and sensory state at the time of the disturbance.