Differences in Transitional Saccades in 4-month-olds When Viewing Pairs of Possible and Impossible Objects

摘要

Previous work demonstrated that 4-month-olds responded with longer looking and increased oculomotor activity toward pictures of impossible cubes relative to possible ones, suggesting infants are able to selectively respond to vertex information that is diagnostic of structural coherence. However, it left open the question of whether 4-month-olds would systematically respond with increased visual interest to other geometrically impossible figures. We tested 4-month-old infants in an eye-tracking paradigm with novel pairs of possible and impossible objects (e.g., ovals, rectangles). We hypothesized that infants would engage in active comparison of the objects and that impossible figures would evoke increased selective looking in order to resolve the global structural anomaly. Infants again fixated longer on the impossible cube relative to the possible one (p .05), and produced a greater number of transitional saccades between the interior critical region and neighboring regions of the impossible relative to the possible cube (p .01). Although dwell times for the other possible-impossible mates did not differ reliably, there were significantly more transitional shifts of gaze between the upper and lower halves of the ovals (p .01) and inner and outer regions of the rectangles (p .05) as a function of possibility. The effect of greater visual interest for impossible shapes did not generalize across all shape pairs. Infants apparently more actively examine some impossible figures, although there is a large amount of variability in infants' fixation behaviors. This may be due to individual differences in selective looking or emerging sensitivity to pictorial depth information, or it may be a stimulus-dependent response that manifests exclusively with certain shapes (e.g., salient manipulations of T-junctions). These findings suggest that some mechanisms for registering pictorial depth and representing 3D object coherence are available early and continue to develop rapidly within the first several months.