Computation for cognitive science: Analog versus digital.

Cognitive science was founded on the idea that the mind/brain can be understood in computational terms. While computational modeling in science is ubiquitous, cognitive science takes the stronger stance that the mind/brain literally performs computations. Moreover, performing computations is crucial to explaining what the mind/brain does, qua mind/brain. Unfortunately, most scientists fail to consider analog computation as a legitimate and theoretically useful type of computation in addition to digital computation; to the extent that analog computation is acknowledged, it is mostly based on a simplistic and incomplete understanding. Taking computation to consist of only one type (i.e., digital) while ignoring another, interestingly distinct type (i.e., analog) leads to an impoverished understanding of what it could mean for minds/brains to compute. A full appreciation and understanding of analog computation-particularly in relation to digital computation-allows researchers to develop computational frameworks and hypotheses in new and exciting ways. Thus, somewhat counterintuitively, looking to the once-dominant computing paradigm of yesteryear can provide novel computational ways of thinking about the mind and brain. This article is categorized under: Philosophy > Foundations of Cognitive Science.

Changes in events alter how people remember recent information.

Observers spontaneously segment larger activities into smaller events. For example, "washing a car" might be segmented into "scrubbing," "rinsing," and "drying" the car. This process, called event segmentation, separates "what is happening now? from "what just happened." In this study, we show that event segmentation predicts activity in the hippocampus when people access recent information. Participants watched narrative film and occasionally attempted to retrieve from memory objects that recently appeared in the film. The delay between object presentation and test was always 5 sec. Critically, for some of the objects, the event changed during the delay whereas for others the event continued. Using fMRI, we examined whether retrieval-related brain activity differed when the event changed during the delay. Brain regions involved in remembering past experiences over long periods, including the hippocampus, were more active during retrieval when the event changed during the delay. Thus, the way an object encountered just 5 sec ago is retrieved from memory appears to depend in part on what happened in those 5 sec. These data strongly suggest that the segmentation of ongoing activity into events is a control process that regulates when memory for events is updated.

The Brain's Cutting-Room Floor: Segmentation of Narrative Cinema.

Observers segment ongoing activity into meaningful events. Segmentation is a core component of perception that helps determine memory and guide planning. The current study tested the hypotheses that event segmentation is an automatic component of the perception of extended naturalistic activity, and that the identification of event boundaries in such activities results in part from processing changes in the perceived situation. Observers may identify boundaries between events as a result of processing changes in the observed situation. To test this hypothesis and study this potential mechanism, we measured brain activity while participants viewed an extended narrative film. Large transient responses were observed when the activity was segmented, and these responses were mediated by changes in the observed activity, including characters and their interactions, interactions with objects, spatial location, goals, and causes. These results support accounts that propose event segmentation is automatic and depends on processing meaningful changes in the perceived situation; they are the first to show such effects for extended naturalistic human activity.