Visual Features: Featural Strength and Visual Strength Are Two Dissociable Dimensions.

Visual features are often assumed to be the general building blocks for various visual tasks. However, it is well known that some stimulus categories (i.e., basic features) can be processed in parallel, but others (e.g., Ts in different orientations) need to be scanned serially, and this difference in featural strength seems to be on a fundamentally different dimension from differences in visual strength (e.g., reduction in contrast). This study compared two high-level tasks, namely tasks that require a lot of attentional operations (change detection and pattern comparison), with one low-level task, namely a task that requires few attentional operations (perceptual discrimination). The results confirmed that featural strength has substantial effects on high-level tasks but only a negligible effect on the low-level task. The results also revealed a complementary interaction: Visual strength has a substantial effect on the low-level task, but a negligible effect on high-level tasks. Overall, featural strength and visual strength are two dissociable dimensions in processing of visual features. The present results, along with other findings, challenge the generality of processing visual features.