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Erik Blaser, Zsuzsa Kaldy, Henry Lo, Marisa Biondi; A salience-mapping method for testing infants' visual working memory for speed vs. luminance. Journal of Vision 2010;10(7):475. doi: 10.1167/10.7.475.
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© ARVO (1962-2015); The Authors (2016-present)
Background. Research on infant cognition has long been concerned with how infants process static vs. moving objects (e.g. Van de Walle & Spelke, 1996; Rakison & Poulin-Dubois, 2002). We are interested in comparing infants' visual working memory (VWM) for speed and luminance. Here we focus on our revised ‘salience-mapping’ technique (Kaldy & Blaser, 2009) that allows us to generate comparison objects with iso-salient differences from a common baseline object, thereby ensuring fair VWM tests. Methods. Subjects' age was 5;0-6;30. A Tobii T120 eye-tracker measured infant' gaze direction. Experiment 1 (ISM): Salience was calibrated in a preferential looking paradigm by pitting a baseline object (a slowly rotating green star) against a range of objects that increased either in luminance or in speed of rotation. Salience functions were obtained for each of the dimensions. We chose speed and luminance values that were at the 75% iso-salience level. In this way we defined three objects that had the following relationship: the salience difference between the baseline and the luminance comparison and the baseline and the speed comparison was equal. Experiment 2 (VWM): In this in-progress experiment, two of the three such defined objects are presented for 3.5 seconds. The two objects disappear for 2 seconds, then reappear, but with one changed in luminance or speed (by the previously calibrated amount) while the other reappears unchanged. Preference, determined from looking time, for the changed (vs. unchanged) object is evidence for memory. Results. Iso-salient differences for luminance and motion were successfully measured in Experiment 1 using our revised salience-mapping technique. While data collection for Experiment 2 is ongoing, we expect better VWM for motion as opposed to luminance. Discussion. In service to VWM experiments, we demonstrated an innovative method for producing psychophysically comparable stimulus differences for infants along the dimensions of speed and luminance.
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