Gilad Ravid

Background and Hypothesis: People with schizophrenia (SCZ) show characteristic impairments in semantic cognition, yet the cognitive mechanisms underlying these patterns remain unclear. Here, we propose a unified mechanistic account in which semantic retrieval is constrained by limitations in internal attention. Specifically, we approximate semantic space as a network of interconnected concepts and posit two attentional control parameters: representational precision (resolution; the ability to distinguish nearby concepts) and the size of the attended field (the subset of semantic space prioritized). We hypothesize that attentional constraints in SCZ reduce precision and/or narrow the attended field, yielding complementary, theoretically predicted patterns of semantic search. Study Design: We first constructed a directed semantic graph using a large sample of individuals performing the animal Category Fluency Test (CFT). We then used this network as a normative reference to analyze fluency-derived paths from SCZ and control participants. Study Results: Relative to controls, CFT paths in the SCZ group showed increased reliance on abstract, category-level structure, and reduced exploration radius. These patterns align with compensatory strategies predicted by the proposed mechanism: reliance on coarse-grained structure when resolution is limited, and restriction of traversal when the effective attended field is narrow. Conclusions: The findings support an attention-constrained retrieval account rather than a stochastic retrieval deficit, indicating that group-level semantic retrieval differences in SCZ may arise from reduced representational resolution and/or a narrowed attended field. These results highlight the value of considering internal attention mechanisms when interpreting semantic impairments in SCZ, with potential connections to attentional phenotypes of ADHD/ADD.