Impaired holistic processing of left-right composite faces in congenital prosopagnosia

Abstract

Congenital prosopagnosia (CP) refers to a lifelong impairment in face processing despite normal visual and intellectual skills. Many studies have suggested that the key underlying deficit in CP is one of a failure to engage holistic processing. Moreover, there has been some suggestion that, in normal observers, there may be greater involvement of the right than left hemisphere in holistic processing. To examine the proposed deficit in holistic processing and its potential hemispheric atypicality in CP, we compared the performance of 8 CP individuals with both matched controls and a large group of non-matched controls on a novel, vertical composite task. In this task, participants judged whether a cued half of a face (either left or right half) was the same or different at study and test, and the two face halves could be either aligned or misaligned. The standard index of holistic processing is one in which the unattended face half influences performance on the cued half and this influence is greater in the aligned than in the misaligned condition. Relative to controls, the CP participants, both at a group and at an individual level, did not show holistic processing in the vertical composite task. There was also no difference in performance as a function of hemifield of the cued face half in the CP individuals, and this was true in the control participants, as well. The findings clearly confirm the deficit in holistic processing in CP and reveal the useful application of this novel experimental paradigm to this population and potentially to others as well.

Normal composite face effects in developmental prosopagnosia

“…We describe two experiments employing independent samples of DP participants collected in the UK and the USA (N = 16 and N = 24) and complementary paradigms (simultaneous and sequential matching). Contrary to previous group studies (Avidan et al, 2011;Liu & Behrmann, 2014;Palermo et al, 2011), we find no evidence for diminished composite face effects in DP.…”

“…In at least one study, inspection of single-case data suggests that previously reported group results have been strongly influenced by the presence of outliers in DP samples (Palermo et al, 2011). In other studies, DP samples perform poorly in the baseline 'misaligned' condition making it hard to interpret putative differences in composite effect susceptibility (Liu & Behrmann, 2014).…”

“…Numerous papers have suggested that diminished holistic face processing may underlie the difficulties seen in DP (Avidan, Tanzer, & Behrmann, 2011;Carbon, Grüter, Weber, & Lueschow, 2007;DeGutis, Cohan, Mercado, Wilmer, & Nakayama, 2012;DeGutis, Cohan, & Nakayama, 2014;Liu & Behrmann, 2014;Lobmaier, Bölte, Mast, & Dobel, 2010;Palermo et al, 2011). Typical face perception appears to involve a rapid parallel analysis, whereby local features are integrated into a unified whole (Farah, Wilson, Drain, & Tanaka, 1998;Maurer, Le Grand, & Mondloch, 2002;McKone & Yovel, 2009;Piepers & Robbins, 2013).…”

“…Although studies have described a number of individuals with DP who exhibit composite effects comparable with those of matched controls (Le Grand et al, 2006;Schmalzl, Palermo, & Coltheart, 2008;Susilo et al, 2010), three studies have concluded that DP is associated with reduced susceptibility to the composite face effect at the group level (Avidan et al, 2011;Liu & Behrmann, 2014;Palermo et al, 2011). Nevertheless, the case for diminished composite effects in DP remains unconvincing.…”

Robust associations between the 20-item prosopagnosia index and the Cambridge Face Memory Test in the general population

“…Many authors also report performance on famous face recognition tests (e.g. [7,15,16]). In addition to scores on computer-based tests, however, self-report measures provide a complementary source of diagnostic evidence.…”