# The Effect and Time Course of Prediction and Perceptual Load on Category-Based Attentional Orienting Across Color and Shape Dimensions

## TL;DR

This study explores how predictions and perceptual load influence attention to objects based on their color or shape over time.

## Contribution

It reveals how prediction and perceptual load independently and interactively affect attentional orienting across different object dimensions.

## Key findings

- Invalid predictions increase N2pc for shape-defined targets but not color-defined ones.
- Prediction and perceptual load interact to affect behavioral accuracy in later processing stages.
- Top-down and bottom-up factors modulate attention differently depending on object dimensions.

## Abstract

Objectives: This study investigated the temporal dynamics of category-based attentional orienting (CAO) under the influences of prediction (top-down) and perceptual load (bottom-up) across color and shape dimensions, combining behavioral and event-related potential (ERP) measures. Methods: Across two experiments, we manipulated predictive validity and perceptual load during a visual search for category-defined targets. Results: The results revealed a critical dimension-specific effect of prediction: invalid predictions elicited a larger N2pc component (indexing attentional selection) for shape-defined targets, but not color-defined targets, indicating that shape CAO relies more heavily on predictive information during early processing. At the behavioral level, a combined analysis of the two experiments revealed an interaction between prediction and perceptual load on accuracy, suggesting their integration can occur at later stages. Conclusions: These findings demonstrate that prediction and perceptual load exhibit distinct temporal profiles, primarily independently modulating early attentional orienting, with their interactive effects on behavior being more nuanced and dimension-dependent. This study elucidates the distinct temporal and dimensional mechanisms through which top-down and bottom-up sources of uncertainty shape attentional orienting to categories.