Abstract
Our visual world is dynamic in nature. The ability to encode, mentally represent, and track an object's identity as it moves across time and space is critical for integrating and maintaining a complete and coherent view of the world. Here we investigated dynamic object processing in typically developing (TD) infants and infants with fragile X syndrome (FXS), a single-gene disorder associated with deficits in dorsal stream functioning. We used the violation of expectation method to assess infants’ visual response to expected versus unexpected outcomes following a brief dynamic (dorsal stream) or static (ventral stream) occlusion event. Consistent with previous reports of deficits in dorsal stream-mediated functioning in individuals with this disorder, these results reveal that, compared to mental age-matched TD infants, infants with FXS could maintain the identity of static, but not dynamic, object information during occlusion. These findings are the first to experimentally evaluate visual object processing skills in infants with FXS, and further support the hypothesis of dorsal stream difficulties in infants with this developmental disorder.
Highlights
Our visual world is dynamic in nature; we move and objects around us move
Preliminary analyses of mean looking time differences between the expected and unexpected outcomes using a repeated measures analysis of variance (ANOVA) showed no effects involving mental age, gender, or trial order; these factors were excluded from the following analyses
Mean looking time during each test trial was entered into a repeated measures ANOVA with two withinsubject factors: outcome and trial pair, and one between-group factor: group
Summary
Our visual world is dynamic in nature; we move and objects around us move. For example, an object can go out of sight as our eye or head position changes, or if moving, it can go out of sight when obstructed by other objects. Previous studies have typically used the preferential looking paradigm to show that from a young age infants look longer at the outcome of a static occlusion event when a feature of the hidden object is changed compared to an event in which features remain the same. Extensive research using this paradigm has provided evidence that the specific features which infants use to discriminate the identity of an object change across development. Less is known about the ability of infants to maintain an object representation during a dynamic occlusion event, namely, whether infants can track a mental representation across time and space (Richardson and Kirkham, 2004)
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