Visual Object Categorization in the Brain: What Can We Really Learn from ERP Peaks?

In three experiments, Dering et al. (2011) measured the amplitude and latency of the mean P1 and N170 in response to faces, cars, and butterflies, cropped or morphed. The N170 was sensitive to cropping but did not differentiate frontal views of faces and cars. Throughout, P1 amplitude was larger for faces than objects. The authors concluded that P1, not N170, is a reliable face-sensitive event. Although Dering et al. (2011) and Thierry et al. (2007) correctly identified problems with P1 and N170 ERP interpretations, these same problems are evident in their own research, and, consequently, their results are equally inconclusive. We identify four shortcomings in Dering et al.’s approach that also apply to the literature they contest (e.g., Eimer, 1998; Allison et al., 1999; Carmel and Bentin, 2002; Itier and Taylor, 2004; Rousselet et al., 2004; Rossion and Jacques, 2008): categorical design, uncontrolled task demands, group statistics, and peak measurements. ERPs are worthwhile measurements of visual processing, but only when the shortcomings reviewed below are addressed.