Sinistrals are rarely “right”: evidence from tool-affordance processing in visual half-field paradigms

Abstract

Although current neuroscience and behavioral studies provide substantial understanding of tool representations (e.g., the processing of tool-related affordances) in the human brain, most of this knowledge is limited to right-handed individuals with typical organization of cognitive and manual skills. Therefore, any insights from these lines of research may be of little value in rehabilitation of patients with atypical laterality of praxis and/or hand dominance. To fill this gap, we tested perceptual processing of man-made objects in 18 healthy left-handers who were likely to show greater incidence of right-sided or bilateral (atypical) lateralization of functions. In the two experiments reported here, participants performed a tool vs. non-tool categorization task. In Experiment 1, target and distracter objects were presented for 200 ms in the left (LVF) or right (RVF) visual field, followed by 200 ms masks. In Experiment 2, the centrally presented targets were preceded by masked primes of 35 ms duration, again presented in the LVF or RVF. Based on results from both studies, i.e., response times (RTs) to correctly discriminated stimuli irrespective of their category, participants were divided into two groups showing privileged processing in either left (N = 9) or right (N = 9) visual field. In Experiment 1, only individuals with RVF advantage showed significantly faster categorization of tools in their dominant visual field, whereas those with LVF advantage revealed merely a trend toward such an effect. In Experiment 2, when targets were preceded by identical primes, the “atypical” group showed significantly facilitated categorization of non-tools, whereas the “typical” group demonstrated a trend toward faster categorization of tools. These results indicate that in subjects with atypically organized cognitive skills, tool-related processes are not just mirror reversed. Thus, our outcomes call for particular caution in neurorehabilitation directed at left-handed individuals.

Specialization of the left supramarginal gyrus for hand-independent praxis representation is not related to hand dominance

“…Notably, no area showed greater activity in right-handers during praxis planning. The one-directional nature of these handedness-related differences is consistent with long-standing evidence that left-handers generally exhibit less cerebral asymmetry of various cognitive functions, including language (Hecaen, De Agostini, & Monzon-Montes, 1981; Hecaen & Sauguet, 1971; Levy & Reid, 1978; see also Michalowski & Kroliczak, 2015; Haberling & Corballis, 2015; Haberling, Steinemann, & Corballis, 2016). By contrast, during the production phase we detected substantial differences in brain activity between groups in both directions.…”

Co-lateralized bilingual mechanisms for reading in single and dual language contexts: evidence from visual half-field processing of action words in proficient bilinguals

“…Christoffels et al, 2007 ; Cheng and Howard, 2008 ). This scenario—a separation of the mechanisms involved in lexical and/or phonological access—is way more likely than any reorganization of the laterality of tool-use concepts, which in the majority of individuals should still be strongly left-lateralized (Króliczak and Frey, 2009 ; Michałowski and Króliczak, 2015 ).…”

Planning Functional Grasps of Simple Tools Invokes the Hand-independent Praxis Representation Network: An fMRI Study

“…From the time of Gibson, functionality of objects is associated with the aforementioned concept of affordances (Gibson, 1977(Gibson, , 1986 typically referring to such characteristics of tools that automatically invoke the most effective actions in their presence. Regardless of whether the general macro-affordances (Mizelle et al, 2013) or more specific micro-affordances (Pellicano, Iani, Borghi, Rubichi, & Nicoletti, 2010;Michalowski & Kroliczak, 2015) are considered, with a notable exception of behavioral studies by Ellis and Tucker (2000), the focus has been usually put on processing of the goal/target-relevant parts of tools, and their impact on other objects.…”