Consistency and idiosyncrasy of semantic categorization by individuals with traumatic brain injuries

Information about semantic categorization consistency may help practitioners to implement augmentative and alternative communication (AAC) options for people with traumatic brain injuries (TBIs). The researchers sought to determine the consistency and extent of general consensus agreement with which adults with TBI organize semantic information.

The researchers compared the semantic categorization consistency of 10 participants with severe TBI to 10 neurotypical adults matched on age and gender. Participants performed a semantic categorization task three times over a 1-month period. The experimental task consisted of two stages: (a) sorting ordinate exemplars into superordinate categories and (b) sorting subordinate exemplars into the previously established ordinate categories.

Results showed that participants with TBI were less consistent across trials and more idiosyncratic than neurotypical peers in placing exemplars within categories. Although some participants with TBI achieved higher general consensus agreement scores with experimental task repetition, their performance did not reach levels comparable to those of neurotypical participants.

Individually, semantic categorization patterns of some people with severe TBI conform to those of neurotypical adults; patterns of others do not. Some, but not all, survivors demonstrate increased consistency given task repetition. These findings have implications for AAC design and instruction for people with TBI. Implications for Rehabilitation Clinicians should evaluate the manner in which an individual with TBI categorizes semantic information rather than assuming that he/she intuitively uses the hierarchical superordinate-ordinate-subordinate categorization pattern common to neurotypical adults. Clinicians should evaluate the consistency with which an individual with TBI categorizes semantic information before determining the manner of organizing content within an AAC system or device. When individuals with TBI display idiosyncratic and/or inconsistent patterns of semantic organization, clinicians should explore the possibility that repeated exposure to specific lexical items or direct instruction about categorization strategies will normalize and/or stabilize performance.