Words and faces: Eccentricity distinguishes crowding from context

Introduction: Features of faces and words (e.g. eyes and letters) are more easily identified when they are presented in their familiar context as opposed to being presented alone or in an unfamiliar arrangement . In the fovea, this is known as the word and face superiority effect, and is evidence that words and faces are special (Reicher, 1969 Journal of Experimental Psychology 81 275 - 280; Tanaka and Farah, 1993 Quarterly Journal of Experimental Psychology 46 225 - 245). However, in the periphery, thes same feature and face stimuli reveal a face inferiority effect (Martelli et al., ECVP 2001). Here we ask what is the nature of the difference in face and word recognition between central and peripheral locations. Specifically we assess the role of crowding, whereby letters in the periphery are harder to identify when other letters are nearby. Method: We measured contrast thresholds for identifying a mouth or a letter in a context that is familiar, unfamiliar, or absent, at various locations in the visual field. We also independently varied the spacing between the features and their size. Results and conclusions: 1. The familiarity effect is independent of eccentricity (unlike crowding). 2. The context inferiority effect has a critical spacing proportional to eccentricity, showing that it is crowding. Thus faces are special at all visual field locations but, as eccentricity increases, crowding limits the observer's ability to distinguish a smile from a frown.