Abstract
Inattentional Blindness (IB) is the failure to notice (or, at least, to report) a salient, but unexpected event. It is a theoretically important phenomenon that may be related to the failure to report “incidental findings”, important items that are not the primary target of search in tasks like medical image analysis or security search. Age, Intelligence Quotient (IQ), and expertise are among the variables proposed to be related in susceptibility to IB. However, the prior results have not been consistent enough to convincingly identify the critical variables. In the present work, we studied a large sample of 277 observers from 4 to 25 years old. All participated in the same visual search task where targets and distractors were real-world objects. On two, separate trials during the task, a letter and a word were presented unexpectedly among the objects. At the end of the task, observers were asked about the letter and the word using both free-recall and recognition questionnaires. All participants were tested on an IQ-proxy test (RIST) and attentional test (Continuous Performance Test - K-CPT or CPT, depending on age). We found significant age differences in IB for both the letter and the word IB stimuli, showing that younger children have more trouble noticing the unexpected stimuli. The age effects on IB differed for the letter and the word, showing that IB can be stimulus-dependent. For word-IB, CPT inattention-related variables also correlated with IB showing higher IB levels for higher inattention levels. Neither gender nor IQ had significant effects on IB. The results show that age and in(attention) can be important variables affecting how distractors are processed in visual search. We did not find evidence for a relationship between IB and measures of intelligence though we note that, as a negative finding, this result should be treated with caution.