Material context moderates the occupation-adjusted association between Visualization and prefrontal hemodynamics during naturalistic design: an exploratory wearable fNIRS study.

It remains unclear whether individual differences in a design-related disposition relate to prefrontal hemodynamics during naturalistic design, and whether the material context of the task moderates any such association. We addressed this using the Visualization subscale of the design attitude measure (DAM), a preference for externalizing ideas visually that we treat here as a continuous disposition beyond the designer job label. Thirty-nine working adults completed an open-ended block-building chair-design task using a constrained material set and a broader, higher-variety material set. Prefrontal total-hemoglobin change was recorded with a wearable two-channel fNIRS device (NeU HOT-2000; Fp1/Fp2; a single 810-nm wavelength; 10 Hz), and each self-paced trial was resampled onto a common proportional-time axis. Visualization was higher in designers than non-designers (d = 1.07). After adjusting for occupation, higher Visualization was associated with a greater broad-constrained Fp2 difference. This Condition × Visualization interaction was localized to a single window at 60-79% of the proportional timeline at Fp2 (cluster-corrected p = 0.013), with no cluster at Fp1; however, the formal between-channel comparison was not significant, so channel specificity was not established. Within this window, the effect remained significant in all 39 leave-one-out refits. The positive simple slope was present under the broad set but not the constrained set; the broad set was also rated as less difficult, more enjoyable, and more conducive to idea generation. Adjusting for occupation increased the whole-design estimate from β = +0.11 to +0.19, because occupation and Visualization related to the Fp2 difference in opposite directions (at a given Visualization level, designer status was associated with a smaller broad-constrained difference), a statistical suppression that separates the visual-externalization disposition from the occupational label; this whole-design estimate was sensitive to one participant. The findings indicate a material-context-dependent association between Visualization (a continuous disposition rather than a proxy for the designer category) and the prefrontal hemodynamic signal, and call for preregistered replication. De-identified data are openly available.