A Unified Attention-Based Account of Semantic Impairment in Schizophrenia

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.