<P> Thus, higher perceptual load, and therefore more significant use of attentional resources, appears to increase the likelihood of inattentional blindness episodes . </P> <P> The theory of inattentional amnesia provides an alternative in the explanation of inattentional blindness in suggesting that the phenomenon does not stem from failures in capture of attention or in actual perception of stimuli, but instead from a failure in memory . The unnoticed stimuli in a visual scene are attended to and consciously perceived, but are rapidly forgotten rendering them impossible to report . In essence, inattentional amnesia refers to the failure in creating a lasting explicit memory: by the time a subject is asked to recall seeing an item, their memory for the stimulus has vanished . </P> <P> While it is difficult to tease apart a failure in perception from one in memory, some research has attempted to shed light on the issue . In a now - classic study of inattentional blindness, a woman carrying an umbrella through a scene goes unnoticed . Despite stopping the video while she is walking through and immediately asking participants to identify which of two people they have seen--leaving as little delay as possible between presentation and report--observers very often fail to correctly identify the woman with the umbrella . No differences in performance were identified whether the video was stopped immediately after the unexpected event or moments later . These findings would seem to oppose the idea of inattentional amnesia, however advocates of the theory could always contend that the memory test simply came too late and that the memory had already been lost . </P> <P> The very phenomenon of inattentional blindness is defined by a lack of expectation for the unattended stimulus . Some researchers believe that it is not inattention that produces blindness, but in fact the aforementioned lack of expectation for the stimuli . Proponents of this theory often state that classic methods for testing inattentional blindness are not manipulating attention per se, but instead the expectation for the presentation of a visual item . </P>

A mental procedure that focuses attention on an external object