How do different training tasks modulate our perception and hemispheric lateralization in the development of perceptual expertise?

Conference Theme: Mind, Technology, and SocietyHolistic processing (HP) and hemispheric lateralization are both expertise markers of object recognition. For example, expertise in face and sub-ordinate object perception is shown to be associated with HP and stronger right hemispheric lateralization. However, HP is modulated by experiences of selective attention to parts such as writing experiences of Chinese characters (Tso, Au, & Hsiao, 2014) and drawing experiences of faces (Zhou et al., 2011). Meanwhile, hemispheric lateralization is associated with the decoding strategy employed in object recognition, such as left hemispheric lateralization for reading alphabetic scripts and right hemispheric lateralization for reading logographic scripts. This study aims at training participants to recognize the same sets of artificially-created scripts using either whole-word (Logographic) or grapheme-to-phoneme (Alphabetic) approaches. We found that both approaches induced strong HP, though the alphabetic approach induced stronger left hemisphere advantage than the logographic approach. This training study demonstrates that HP and hemispheric lateralization are separate processes that are associated with different perceptual mechanisms.postprin

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

Fulltext in: http://mindmodeling.org/cogsci2013/papers/0429/paper0429.pdfDrawing 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

Bilingual Experience Modulates Hemispheric Lateralization in Visual Word Processing

Previous studies showed reduced hemispheric asymmetry in face perception in bilinguals compared with monolinguals, suggesting that hemispheric asymmetry in visual stimulus processing may be modulated by language reading experience. Here we examined whether this phenomenon can also be observed in bilinguals with different language backgrounds. We compared English monolinguals, European–English bilinguals (who know two alphabetic languages), and Chinese–English bilinguals (who have mastered a logographic and an alphabetic language) in an English word sequential matching task. We showed that European–English bilinguals had a stronger right visual field/left hemispheric advantage than the other two groups, suggesting that different language experiences can influence how visual words are processed in the brain. In addition, by using a computational model that implements a theory of hemispheric asymmetry in perception, we showed that this lateralization difference could be accounted for by the difference in participants’ vocabulary size and the difference in word-to-sound mapping between alphabetic and logographic languages.published_or_final_versio

Differential effects of script system acquisition and social immersion experience on face perception

Informelle Berichte zeigten größere Amplituden der durch Gesichter ausgelösten N170 Komponente im Ereigniskorrelierten Potenzial (EKP) bei asiatischen als bei kaukasischen Probanden. Als mögliche Ursache vermutete ich unterschiedliche Erfahrungen mit logographischen bzw. alphabetischen Schriftsystemen (Schriftsystem-Hypothese) oder die verstärkte Exposition mit unbekannten Gesichtern während der Immersion in eine neue soziale oder ethnische Umgebung (soziale Immersions-Hypothese). Zur Überprüfung dieser Hypothesen führte ich zwei kulturvergleichende Studien mit Erwachsenen bzw. Kindern durch. In Studie 1 untersuchte ich einheimische Chinesen und nicht-chinesische Auswärtige in Hongkong und deutsche Einheimische und chinesische Auswärtige in Berlin. Die Auswärtigen an beiden Orten zeigten größere N170 Amplituden auf Gesichter als die Einheimischen. Außerdem zeigten Deutsche, die erst kurze Zeit in Berlin lebten ähnliche Amplituden wie langjährige Einheimische. Insgesamt unterstützt Studie 1 die soziale Immersions-Hypothese, dass die Immersion in eine neue ethnische Umgebung zu einer Vergrößerung der N170 führt. Studie 2 untersuchte die Schriftsystem-Hypothese bei chinesischen und deutschen Erstlesern am Ende der ersten oder zu Beginn des zweiten Schuljahres an ihrem jeweiligen Heimatort. Die Ergebnisse unterstützen die Schriftsystem-Hypothese, dass chinesische Kinder eine größere N170 auf Gesichter zeigen als deutsche. Insgesamt konnte die vorliegende Dissertation zwei neue Einfluss-Faktoren auf das Gesichterverarbeitungs-System nachweisen, das erworbene Schriftsystem (logographische versus alphabetisch) und die Erfahrung sozialer Immersion in eine neue ethnische Umgebung. Diese Effekte zu ganz unterschiedlichen Zeitpunkten der Entwicklung (Kindheit vs. junges Erwachsenen-Alter) zeigen, dass das Gesichterverarbeitungs-System über lange Zeit seine Plastizität behält.Informal reports have shown larger face-elicited N170 component of event-related potential (ERP) in Asians than Caucasians participants. I proposed that different experience with logographic versus alphabetic scripts (script system hypothesis) or by exposure to abundant novel faces during the immersion into a new social and/or ethnic environment (social immersion hypothesis) as a possible cause. To test these hypotheses, I conducted two cross-cultural ERP studies with adults and Children. In Study 1, I examined Chinese locals and non-Chinese foreigners in Hongkong, and German locals and Chinese foreigners in Berlin. It turned out that the foreigners in both locations showed larger N170 amplitudes to faces than the locals. In addition, Germans who had only lived in Berlin for a short time showed similar face N170 amplitudes as long-term Berlin residents. In sum, Study 1 supports the social immersion hypothesis that immersing into a new ethnic environment drives an increase of face N170. Study 2 investigated the scripts system hypothesis in Chinese and German early readers assessed at the end of the first-grade or at the beginning of the second grade in their respective home towns. The findings support the script system hypothesis that Chinese children showed larger face N170 amplitudes than German children. Overall, the present thesis demonstrated two new influencing factors on the face processing system, the acquired script system (logographic vs. alphabetic) and the social immersion experience in a new ethnic environment. More specifically, learning to read a visually complex logographic Chinese script or immersing into an other-ethnic social environment facilitates early perceptual processing of faces. These effects acquired at different stages of development (early childhood versus young adulthood) show that the face processing system retains its plasticity over a long period of time

Capacity Limits in Visual Processing Revealed by Spatial Biases

Our early visual system extracts fine grained information about our rapidly changing world, yet in certain laboratory conditions, participants fail to report some items that are clearly presented within their field of vision. These failures are likely to occur because later stages of the visual system do not have capacity to process all of the information extracted at the retina. In this thesis, I investigate a particular failure of awareness that occurs when two target letters are briefly presented at the same time in different spatial locations. A clue to the cause of these failures may lie in the spatial pattern of errors that participants make. A recent theory suggests that the consistency in spatial errors across participants may reflect a functional strategy used by the brain to prioritise information at a key processing bottleneck. I investigate this claim, and conduct research to investigate other aspects of the limitation, such as the processing stage at which it occurs, and its implications for visual processing tasks such as reading