Computational exploration of task and attention modulation on holistic processing and left side bias effects in face recognition: the case of face drawing experts

Computational exploration of task and attention modulation on holistic processing and left side bias effects in face recognition: the case of face drawing experts. Bruno Galmar (brunogal@hku.hk) Janet Hui-wen Hsiao (jhsiao@hku.hk) Department of Psychology, University of Hong Kong Pokfulam Road, Hong Kong SAR Abstract Drawing artists and non-drawers are like any adult both experts at face recognition. Yet, artists have a richer learning experience with faces: they were trained in rapid sketching of faces. Zhou, Cheng, Zhang and Wong (2011) found that drawing experts showed less holistic processing (HP) for face recognition than non-drawers. Using a computational model of face recognition that did not implement motor processing, we examined whether engagement of local attention and nature of the learning task could account for the reduced HP in drawers without the influence from motor experience. We showed that compared with the non-drawer model that had a global face input (i.e., Hsiao, Shieh & Cottrell, 2008), a drawer model that incorporated both global face and local facial parts (eyes and mouth) in the input showed reduced HP, suggesting the modulation of local attention engagement. In contrast, the other drawer model that used only global face input but learned to perform an additional face part identification task did not show the reduced HP effect. In addition, both drawer models demonstrated stronger left side (right hemisphere) bias than the non-drawer model. Our data thus suggest that engagement of local attention is sufficient to account for the reduced HP in drawers, and that HP and left side bias effects can be differentially modulated by visual attention or task requirements. Keywords: Model of face recognition; Holistic processing; Hemispheric lateralization; Visual expertise. Introduction Visual expertise in subordinate-level discrimination has been extensively studied (e.g., Bukach, Gauthier, & Tarr, 2006), such as our expertise in recognizing individual faces. Several behavioral markers of visual expertise have been identified, including holistic processing (HP), which refers to the phenomenon of viewing faces as a whole instead of various parts (Bukach et al., 2006; although some argue that HP is specific to face recognition; e.g., McKone, Kanwisher, & Duchaine, 2007). Subsequent studies suggest a correlation between an increase in HP and expertise in subordinate-level individualization, as opposed to expertise in basic-level categorization (e.g., Wong, Palmeri, & Gauthier (2009)). For example, Wong et al. (2009) trained two participant groups to recognize an artificial object type (Ziggerins) with different training tasks: one group learned to rapidly individualize Ziggerins at the subordinate level, whereas the other group learned rapid sequential categorization at the basic level. The results showed that only the individuation experts showed an increase in HP, even though the two groups had the same amount of exposure to Ziggerins. This suggests that qualitatively different expertise processing can arise depending on the nature of the training task. Such a qualitative difference of expertise processing resulting from different learning and training experience has been recently observed for face recognition. Zhou, Cheng, Zhang and Wong (2011) studied two groups: (a) an experimental group was composed of art students who had extensive formal training in sketching and drawing portraits, and (b) a control student group of non-drawers – i.e. who had no prior drawing background or education-. Hence, the two groups had different learning experience in processing faces. Non-drawers would show the typical face expertise any adult is endowed with: being able to recognize at least a thousand of faces. In contrast, art students would have internally assimilated an ordered procedure for rendering faces on a 2D surface (Balas & Sinha, 2007; Willenbrink & Willenbrink, 2012), for example: a) sketch the basic head proportion, b) sketch the overall head form and basic lines for features, c) place the brows and lips, and so on. Such a fine-grained procedure relies upon a mix of global and local processing, and featural and configural processing. Art students would not ignore face details which are critical to render a vivid portrait of an individual. Hence, art students are used to scrutinize a face and could be less engaged in HP than non-drawers. This educative guess is supported by eye-tracking studies (Miall & Tchalenko, 2001; Tchalenko et al. 2003) of eye movements of a skilled artist. Miall and Tchalenko (2001) proposed as an account of the visual encoding of the studied artist Ho: ―The capture of visual information detail by detail, rather than in a more holistic manner, is reflected in the way the drawing or painting is built up. Each detail and each element is of intrinsic importance. ‖ Using the complete composite paradigm of face recognition, Zhou et al. (2011) found less HP for art students than for non-drawers. Reduced HP with drawing expertise is not an isolate case. Previously, Hsiao and Cottrell (2009) found reduced HP for Chinese readers - who were experts at recognizing Chinese characters - compared with novice Chinese readers. Tso, Au, and Hsiao (2011) further showed that the reduction in HP found in expert Chinese readers depended on their writing rather than reading experience of Chinese characters, since proficient readers who had limited writing experience (i.e. Limited- writers) showed increased HP as compared with novices, in contrast to the reduced HP observed in Chinese readers who could read and write fluently (i.e., Writers; Tso, 2012).