LAUSR

The dynamics of selective attention necessarily influences the course of early perceptual development. The intersensory redundancy hypothesis proposes that in early development information presented redundantly across two or more senses selectively recruits attention to the amodal properties of an object or event. In contrast, information presented to a single sense enhances attention to modality-specific properties. The present study assessed the second of these predictions in neonatal bobwhite quail (Colinus virginianus), with a focus on the role of task difficulty in directing selective attention. In Experiment 1, we exposed quail chicks to unimodal auditory, nonredundant audiovisual, or redundant audiovisual presentations of a bobwhite maternal call paired with a pulsing light for 10 min/h on the day following hatching. Chicks were subsequently individually tested 24 h later for their unimodal auditory preference between the familiarized maternal call and the same call with pitch altered by two steps. Chicks from all experimental groups preferred the familiarized maternal call over the altered maternal call. In Experiment 2, we repeated the exposure conditions of Experiment 1, but presented a more difficult task by narrowing the pitch range between the two maternal calls during testing. Chicks in the unimodal auditory and nonredundant audiovisual conditions preferred the familiarized call, whereas chicks in the redundant audiovisual exposure group showed no detection of the pitch change. Our results indicate that early discrimination of pitch change is disrupted by intersensory redundancy under difficult but not easy task conditions. These findings, along with findings from human infants, highlight the role of task difficulty in shifting attentional selectivity and underscore the dynamic nature of neonatal attentional salience hierarchies.