Thesis advisor: Ellen Winner / Individuals with Autism Spectrum Disorder (ASD) have been shown to have a local processing bias: they are able to focus on the details of a visual display and ignore the overall whole and context (Mottron & Belleville, 1993; Mottron, Belleville, & Ménard, 1999). Typical individuals with the ability to draw realistically also show this local bias (Drake, Redash, Coleman, Haimson, & Winner, 2010; Drake & Winner, 2011). Two opposing theories have been proposed to account for the local processing bias in individuals with ASD. Some have argued that the local processing bias is at the expense of the ability to grasp the whole and that these individuals lack a "global bias" (Happé & Frith, 2006). According to this view, individuals with ASD have "weak central coherence." Mottron and his colleagues, however, have suggested that the local processing bias seen in ASD exists alongside intact global processing (Mottron & Belleville, 1993; Mottron et al., 1999). According to this view, individuals with ASD have "enhanced perceptual functioning." However, it is likely that these classifications overlook individual variations in local and global processing in the ASD and non-ASD population, some ASD and non-ASD individuals strong in both, weak in both, strong only in local, or strong only in global. If so it would be important to determine the predictors of each pattern, whether the same patterns of individual differences exist in the ASD and non-ASD population, and whether the predictors of each pattern are the same for ASD and non-ASD individuals. Four predictors of local and global processing (as assessed by a battery of tasks) were investigated: verbal IQ, nonverbal IQ, realistic drawing skill, and severity of ASD diagnosis. Participants in study 1 were non-ASD children; Participants in study 2 were ASD children; and those in study 3 were the combined sample of ASD and non-ASD children. Four major findings emerged. First, the predictors of local and global processing skill in the ASD population are the same as those in the non-ASD population. Second, the strongest predictor of local and global processing skills was realistic drawing skill, and not diagnosis, a novel finding. Third, as a group, ASD individuals performed no better and no worse on either local or global processing tasks than did non-ASD individuals, again a surprising and novel finding. Finally, and consistent with finding #2, children with strong performance in local and global processing also scored high in both drawing realism and nonverbal IQ. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.

No description available.

Perceptual grouping describes the organization of small elements into larger objects. Research in user interface (UI) design has demonstrated effects of perceptual grouping on attention and navigation. However, grouping can be mediated by a variety of task factors. One such mediator is processing time. Recent discoveries in vision science suggest that elemental grouping can occur in more than one way, depending on how long elements are displayed. These findings have led to a new understanding of perceptual organization of elements in real-world spatial environments. However,these findings had not been explored within the context of UI environments. Time limits to UI are often set by task demands. Exposure time limits may affect perceptual grouping of elements in UI. Here I report a series of experiments that tested global and local pushbutton grouping by time in user interface displays. The research question was to determine whether global or local depictions of pushbutton groupings speed interaction with user interface. Global and local groupings were compared because prior researchers have discovered that global scene properties can be perceived before local scene properties. For this reason, it was hypothesized that global, as opposed to local, depictions of pushbutton groupings would speed human-interface interactions. Global grouping was defined as grouping by relatively large shapes whereas local grouping was defined as grouping by shapes that were relatively small. The difference between global and local grouping was quantitative and defined by comparison. Participants saw pushbutton interface displays on a computer monitor for varied exposure durations and were asked to make decisions about the grouping of pushbuttons in these displays. Responses and reaction times were recorded. The results of the reported experiments suggest that global, as compared to local, groupings are more accessible across stimulus durations. They also suggest that global groupings can be utilized faster than local groupings in unlimited exposures. Taken together, the reported results further our understanding of global and local Gestalt grouping in user interface displays.

Ces travaux ont pour but d'explorer le traitement musical chez les personnes présentant un trouble du spectre autistique (TSA). Cette question a été abordée sous l'angle des traitements global et local dans le cadre des deux théories cognitives dominantes de l'autisme : i) la faiblesse de cohérence centrale et ii) la théorie du surfonctionnement perceptif. Ces deux théories postulent la présence d'un biais de traitement envers l'information locale dans l'autisme provenant, soit i) d'un déficit du traitement global, soit ii) d'une capacité perceptive supérieure. A travers une dizaine d'études, nous avons confronté ces deux théories manipulant les traitements global et local dans la musique. Nous avons aussi questionné la perception auditive chez ces personnes ainsi que son impact sur des traitements de plus haut niveau. Dans l'ensemble, nos travaux mettent en évidence une plus grande implication des processus perceptifs dans le traitement musical chez ces personnes, allant dans le sens de la théorie du surfonctionnement perceptif. Par ailleurs, certains de nos résultats pointent un mécanisme cognitif central chez les personnes autistes : le mécanisme de cartographie véridique. / This research aimed to explore musical processing in individuals with an autistic spectrum disorder. This question has been tackled by exploring global and local processing in the framework of the two main cognitive theories of autism: i) the weak central coherence theory and ii) the enhanced perceptual processing theory. These two theories postulate a bias toward local processing in autism which originates either from i) a global processing deficit or ii) enhanced perceptual capacities. Through ten studies, we confronted these two theories by manipulating global and local processing of music. We also explored auditory perception in autistic people and its impact on higher musical processing. Globally, our research highlights a greater implication of perceptual processes in musical processing, giving support to the enhanced perceptual processing theory. In addition, some of our results point to a central cognitive mechanism in autism: the mechanism of veridical mapping.

No description available.

Pas de résumé / The thesis investigated the development of children’s global/local processing hierarchical patterns introduced by Navon (1977). The objectives were to understand more comprehensively the developmental characteristics of children’s perception through their global and local processing of hierarchical patterns, by considering the effects of age, stimuli properties, duration of exposure to the stimuli and gender in a perceptual task and a drawing task. These effects were tested in 3 different populations: typically developing children, children with mental retardation and early blind children. The results revealed that typically developing children attended to both the local and global level of processing but these modes of spatial information processing operated independently. In a first step, children before 4 years of age showed dominance of local processing and then a more global processing developed at 4 years of age, and at 5 years of age integrated responses began to emerge. Early blind children showed similar developmental characteristics, although there was a protracted period of local processing dominance. Indeed, these children mainly produced local responses at ages of between 6 and 10 years, and then developed more global responses at 11-12 years and continued to integrate the two levels of analysis at later ages. On the other hand, global dominance was shown in children with mental retardation and their development was affected more by mental age than by chronological age. Moreover, their responses were shown to be sensitive to the fact that meaningful object could be located at the local level, enhancing local processing in this case. These results need further confirmations as the studies of global/local processing in atypical children are not numerous. In particular, the effect of duration of exposure to the stimuli should be further analyzed, because this factor did not seem to have a great effect in our experiments while it seemed more powerful in other studies carried out with adults. Replication of the study with children with mental retardation appears also important to plan for future work, because we can have some doubt relatively the absence of modification through ages of the way these children perceive hierarchical patterns. Finally, defining more precisely what may underlie the gender differences seems also worth to explore since gender did not show a major effect in our results.

<p>Three main theories have been proposed to account for the completion of occluded objects, namely local theories (e.g., Kellman & Shipley, 1991), global theories (e.g., Boselie & Leeuwenberg, 1986), and integrative models of completion (e.g., Sekuler, 1994; van Lier et al., 1994). Here, we investigated age-related changes in the completion of a complex partially occluded object using a prime-matching task. Subjects were shown a prime (global, local, occluded, or no prime) that was followed immediately by two shapes that were judged as being the same or different. In Experiment 1, we tested adults (n = 36/group) at various prime durations (150 - 700 msec) to tap into earlier and later representations of the occluded object. Although the occluded object primed both the global and local shapes at 150 and 500 msec (<em>p</em>s<0.05), only the global shapes were primed at 300 and 700 msec (<em>p</em>s<0.05). Overall, our results are most consistent with integrative models of completion. In Experiment 2, we tested 8-year-olds (n = 20) at a prime duration of 700 msec and 11-year-olds (n = 30/group) at a prime duration of 300 or 700 msec. For 11-year-olds, unlike adults, the occluded object did not significantly prime either the global or local shapes at 300 msec (<em>p</em>>0.50). For both 8- and 11-year-olds, the global, local, and occluded primes did not significantly prime either shape at 700 msec (<em>p</em>s>0.50). Based on the current testing conditions, we found that the perceptual completion process may not be adult-like even at 11 years of age.</p> / Master of Science (MSc)

The thesis investigated the development of children's global/local processing hierarchical patterns introduced by Navon (1977). The objectives were to understand more comprehensively the developmental characteristics of children's perception through their global and local processing of hierarchical patterns, by considering the effects of age, stimuli properties, duration of exposure to the stimuli and gender in a perceptual task and a drawing task. These effects were tested in 3 different populations: typically developing children, children with mental retardation and early blind children. The results revealed that typically developing children attended to both the local and global level of processing but these modes of spatial information processing operated independently. In a first step, children before 4 years of age showed dominance of local processing and then a more global processing developed at 4 years of age, and at 5 years of age integrated responses began to emerge. Early blind children showed similar developmental characteristics, although there was a protracted period of local processing dominance. Indeed, these children mainly produced local responses at ages of between 6 and 10 years, and then developed more global responses at 11-12 years and continued to integrate the two levels of analysis at later ages. On the other hand, global dominance was shown in children with mental retardation and their development was affected more by mental age than by chronological age. Moreover, their responses were shown to be sensitive to the fact that meaningful object could be located at the local level, enhancing local processing in this case. These results need further confirmations as the studies of global/local processing in atypical children are not numerous. In particular, the effect of duration of exposure to the stimuli should be further analyzed, because this factor did not seem to have a great effect in our experiments while it seemed more powerful in other studies carried out with adults. Replication of the study with children with mental retardation appears also important to plan for future work, because we can have some doubt relatively the absence of modification through ages of the way these children perceive hierarchical patterns. Finally, defining more precisely what may underlie the gender differences seems also worth to explore since gender did not show a major effect in our results.