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Chen Cheng, Zsuzsa Kaldy, Erik Blaser; Accounting for cognitive effort in a visual working memory task in 13- and 15-month old infants. Journal of Vision 2016;16(12):67. doi: 10.1167/16.12.67.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction. Development brings improvements in visual working memory performance, but it is not clear whether this is caused by an increase in memory capacity per se, or by increases in cognitive effort and/or task engagement. Through pupillometric measures and behavioral coding of task engagement during a Delayed Match Retrieval task (Kaldy, Guillory, & Blaser, 2015), we sought to tease these factors apart. Method. Two groups of infants (younger, mean age = 13.6 months, and older, mean age = 15.5 months; N=16) performed 12 trials of an object-location binding task requiring anticipatory looks to the remembered locations of matching (virtual) cards. We video-recorded participants while a Tobii T120 eye-tracker monitored gaze and pupil dilation. Subsequently, three observers (blind to the events on the screen) scored infants' disengagement by timing periods when the infant looked away from the screen. Cognitive effort was measured through phasic, task-evoked pupil responses. Results. As expected, older infants significantly outperformed younger infants on the memory task (F(1,15) = 7.422, p = .015). This age difference could not be explained by disengagement episode counts (F(1,15) = .996, p = .33) nor accumulated disengagement time (F(1,15) = 1.449, p = .247). However, pupillometry revealed significantly greater task-evoked responses in the older group during the critical 'encoding' phase of the memory task, when to-be-remembered stimuli were presented (see supplemental material). Conclusion. Our results show that cognitive effort, as measured by task-evoked pupil responses, is likely a better predictor of performance than more global measures of disengagement, such as looks away from the screen. Further pupillometric analyses will enable the precise quantification the role of cognitive effort in infants' visual working memory performance.
Meeting abstract presented at VSS 2016
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