Inattentional blindness in medicine.

People often fail to notice unexpected stimuli when their attention is directed elsewhere. Most studies of this "inattentional blindness" have been conducted using laboratory tasks with little connection to real-world performance. Medical case reports document examples of missed findings in radiographs and CT images, unintentionally retained guidewires following surgery, and additional conditions being overlooked after making initial diagnoses. These cases suggest that inattentional blindness might contribute to medical errors, but relatively few studies have directly examined inattentional blindness in realistic medical contexts. We review the existing literature, much of which focuses on the use of augmented reality aids or inspection of medical images. Although these studies suggest a role for inattentional blindness in errors, most of the studies do not provide clear evidence that these errors result from inattentional blindness as opposed to other mechanisms. We discuss the design, analysis, and reporting practices that can make the contributions of inattentional blindness unclear, and we describe guidelines for future research in medicine and similar contexts that could provide clearer evidence for the role of inattentional blindness.

Are Familiar Objects More Likely to Be Noticed in an Inattentional Blindness Task?

People often fail to notice the presence of unexpected objects when their attention is engaged elsewhere. In dichotic listening tasks, for example, people often fail to notice unexpected content in the ignored speech stream even though they occasionally do notice highly familiar stimuli like their own name (the "cocktail party" effect). Some of the first studies of inattentional blindness were designed as a visual analog of such dichotic listening studies, but relatively few inattentional blindness studies have examined how familiarity affects noticing. We conducted four preregistered inattentional blindness experiments (total N = 1700) to examine whether people are more likely to notice a familiar unexpected object than an unfamiliar one. Experiment 1 replicated evidence for greater noticing of upright schematic faces than inverted or scrambled ones. Experiments 2-4 tested whether participants from different pairs of countries would be more likely to notice their own nation's flag or petrol company logo than those of another country. These experiments repeatedly found little or no evidence that familiarity affects noticing rates for unexpected objects. Frequently encountered and highly familiar stimuli do not appear to overcome inattentional blindness.

Individual differences in inattentional blindness.

People often fail to notice unexpected objects and events when they are performing an attention-demanding task, a phenomenon known as inattentional blindness. We might expect individual differences in cognitive ability or personality to predict who will and will not notice unexpected objects given that people vary in their ability to perform attention-demanding tasks. We conducted a comprehensive literature search for empirical inattentional blindness reports and identified 38 records that included individual difference measures and met our inclusion criteria. From those, we extracted individual difference effect sizes for 31 records which included a total of 74 distinct, between-groups samples with at least one codable individual difference measure. We conducted separate meta-analyses of the relationship between noticing/missing an unexpected object and scores on each of the 14 cognitive and 19 personality measures in this dataset. We also aggregated across personality measures reflecting positive/negative affectivity or openness/absorption and cognitive measures of interference, attention breadth, and memory. Collectively, these meta-analyses provided little evidence that individual differences in ability or personality predict noticing of an unexpected object. A robustness analysis that excluded samples with extremely low numbers of people who noticed or missed produced similar results. For most measures, the number of samples and the total sample sizes were small, and larger studies are needed to examine individual differences in inattentional blindness more systematically. However, the results are consistent with the idea that noticing of unexpected objects or events differs from deliberate attentional control tasks in that it is not reliably predicted by individual differences in cognitive ability.

Still little evidence sex differences in spatial navigation are evolutionary adaptations.

A putative male advantage in wayfinding ability is the most widely documented sex difference in human cognition and has also been observed in other animals. The common interpretation, the sex-specific adaptation hypothesis, posits that this male advantage evolved as an adaptive response to sex differences in home range size. A previous study a decade ago tested this hypothesis by comparing sex differences in home range size and spatial ability among 11 species and found no relationship. However, the study was limited by the small sample size, the lack of species with a larger female home range and the lack of non-Western human data. The present study represents an update that addresses all of these limitations, including data from 10 more species and from human subsistence cultures. Consistent with the previous result, we found little evidence that sex differences in spatial navigation and home range size are related. We conclude that sex differences in spatial ability are more likely due to experiential factors and/or unselected biological side effects, rather than functional outcomes of natural selection.

Similarity of an unexpected object to the attended and ignored objects affects noticing in a sustained inattentional blindness task.

When focusing attention on some objects and ignoring others, people often fail to notice the presence of an additional, unexpected object (inattentional blindness). In general, people are more likely to notice when the unexpected object is similar to the attended items and dissimilar from the ignored ones. Perhaps surprisingly, current evidence suggests that this similarity effect results almost entirely from dissimilarity to the ignored items, and it remains unclear whether similarity to the attended items affects noticing. Other aspects of similarity have not been examined at all, including whether the similarity of the attended and ignored items to each other affects noticing of a distinct unexpected object. We used a sustained inattentional blindness task to examine all three aspects of similarity. Experiment 1 (n = 813) found no evidence that increasing the similarity of the attended and ignored items to each other affected noticing of an unexpected object. Experiment 2 (n = 610) provided some of the first compelling evidence that similarity to the attended items - in addition to the ignored items - affects noticing. Experiment 3 (n = 1,044) replicated that pattern and showed that noticing rates varied with the degree of similarity to the ignored shapes but not to the attended shapes, suggesting that suppression of ignored items functions differently from the enhancement of attended items.