Contextual grouping cues modulate holistic face perception

Facial features are processed interactively and integrated into a holistic perceptual unit, unlike those within objects, which are processed in a more feature-based manner. This holistic nature of face perception is robust even when discouraged via explicit task instructions. However, it is unclear whether holistic perception mechanisms are truly impenetrable or whether instead perceptual cues that discourage the grouping together of facial features might disrupt such mechanisms. The degree to which faces were perceived holistically was assessed in the context of perceptual cues that either encouraged or discouraged the grouping of information within the faces. Holistic perception was measured using a composite task that required participants to make same/different judgments about a cued part (either the top or bottom) of sequentially presented chimeric faces. This task indexes holistic perception by measuring the degree to which performance is impacted by the task-irrelevant face halves. Here, the face halves appeared against the backdrop of different rectangles, which were either aligned or misaligned – although, critically, the face parts themselves remained aligned. In the misaligned condition, the color of the two background rectangles also differed from each other, a manipulation designed to further discourage the grouping together of the two parts. Results revealed that holistic face perception was significantly modulated by grouping context: when the color and alignment of the background rectangles discouraged perceptual grouping of the face parts, the faces were processed less holistically than when the rectangle features encouraged grouping. Consistent with the notion that this effect reflected disrupted holistic processing, the same grouping cues failed to similarly impact performance involving non-face objects (e.g., cars), which are typically not linked with holistic processing. This contextual influence on holistic face perception is striking, given previous evidence of the impenetrability of holistic face perception.