Environmental volatility is associated with adaptive caution in visual search

Real-world distractors occur in environments whose states change at different rates. We asked whether such volatility alters initial overt oculomotor allocation, later target verification and response commitment, or both. Observers performed an additional-singleton search task with concurrent eye tracking while distractor presence followed high- or low-volatility sequences, with overall distractor prevalence held constant. Trial-pooled oculomotor capture was higher under high volatility, a pattern that appears to indicate altered filtering. Matching the same-location run position removed that difference, with no detectable difference in capture across volatility regimes at matched run position. The pooled capture effect was therefore consistent with a structural consequence of the volatility manipulation, which enriched high-volatility blocks with early-run positions where capture is intrinsically high. The volatility effect itself appeared on distractor-absent trials. Under high volatility, response times were longer, fixations more frequent, final-target dwell longer, and errors fewer, while target-acquisition latency itself was unchanged. Same-location repetition learning showed no detectable difference in slope across regimes. A hierarchical drift-diffusion model (DDM) and a complementary volatility Kalman-filter (VKF) comparison converged in showing that manual responses carried both boundary-related and drift-related structure. With distractor frequency held constant, the per-trial effect of volatility therefore emerged after the first saccade as an increase in response caution rather than in oculomotor capture. This pattern is consistent with precision-weighted adjustment to environmental uncertainty.