Location representation in enclosed spaces: What types of information afford young children an advantage?

It has been suggested that young children can only reorient, locating a target object, when the geometry of an enclosed space provides distinctive shape information [e.g., Hermer, L., & Spelke, E. (1994). A geometric process for spatial reorientation in young children. Nature, 370, 57-59]. Recently, however, young children were shown to specify location in a square-shaped space, where geometry is uninformative, so long as scale-like information was available on the walls of the space [Huttenlocher, J., & Lourenco, S. F. (2007a). Coding location in enclosed spaces: Is geometry the principle? Developmental Science, 10, 741-746]. Here we build on this work by examining more closely what types of cues afford 18- to 24-month-olds an advantage in locating a target object following disorientation. Their performance was assessed when linear scale-like information was presented either in isolation or in composite form. It was found that, even in isolation, young children searched at the appropriate locations, with added benefit when presented as a composite. We suggest that linear scale-like dimensions, especially when available in composite form, play a critical role in supporting location representation in young children.     

A study of syntactic processing in aphasia I: behavioral (psycholinguistic) aspects

This paper presents the results of a study of syntactically based comprehension in aphasic patients. We studied 42 patients with aphasia secondary to left hemisphere strokes and 25 control participants. We measured off-line, end-of-sentence, performance (accuracy and reaction time) in two tasks that require comprehension--enactment and sentence-picture matching--and in grammaticality judgment, with whole sentence auditory presentation. We also used sentence-picture matching and grammaticality judgment as tasks in two self-paced listening studies with the same patients to measure on-line performance. In each task and presentation format, we presented sentences that tested the ability to assign and interpret three structural contrasts chosen to examine different basic syntactic operations: actives and passives, subject and object extracted relative clauses, and reflexive pronouns and matched sentences without these elements. We examined these behavioral data to determine patterns of impairment in individual patients and in groups of patients, using correlational analyses, factor analyses, and analyses of variance. The results showed that almost no individual patients had stable deficits referable to the ability to interpret individual syntactic structures, that a variety of structural features contributed to sentence processing complexity both on-line and off-line, that correct responses were associated with normal on-line and errors with abnormal performance, and that the major determinant of performance is a factor that affected performance on all sentence types. The results indicate that the major cause of aphasic impairments of syntactically based comprehension are intermittent reductions in the processing capacity available for syntactic, interpretive, and task-related operations.     

A study of syntactic processing in aphasia II: neurological aspects

This paper presents the results of a study of the effects of left hemisphere strokes on syntactically-based comprehension in aphasic patients. We studied 42 patients with aphasia secondary to left hemisphere strokes and 25 control subjects for the ability to assign and interpret three syntactic structures (passives, object extracted relative clauses, and reflexive pronouns) in enactment, sentence-picture matching and grammaticality judgment tasks. We measured accuracy, RT and self-paced listening times in SPM and GJ. We obtained magnetic resonance (MR) and 5-deoxyglucose positron emission tomography (FDG PET) data on 31 patients and 12 controls. The percent of selected regions of interest (ROIs) that was lesioned on MR and the mean normalized PET counts per voxel in ROIs were calculated. In regression analyses, lesion measures in both perisylvian and non-perisylvian ROIs predicted performance. Patients who performed at similar levels behaviorally had lesions of very different sizes, and patients with equivalent lesion sizes varied greatly in their level of performance. The data are consistent with a model in which the neural tissue that is responsible for the operations underlying sentence comprehension and syntactic processing is localized in different neural regions in different individuals.