Do the hemispheres differ in their preparation for global/local processing?

Abstract

It has recently been suggested that hemispheric diVerences for global and local processing already occur in response to visual pre-cues that direct attention to a speciWc level. However, in the supporting studies cue information was confounded with the form of the cues. In order to dissolve the confound, we compared event-related brain potentials towards cues diVering in form with those towards identically formed color cues. As a result, hemispheric diVerences were found only for the former cue type. The data thus show that the mere cue information does not produce hemispheric asymmetries associated with global/local target stimulus processing.

Functional hemispheric asymmetries of global/local processing mirrored by the steady-state visual evoked potential

“…Furthermore, we can assume that the processing of global and local information per se is not lateralised as is indicated by the results that no hemispheric asymmetries were seen when binding was not behaviourally relevant (in response to the cue and to congruent stimuli). Although null findings can result from lack of statistical power, they are in line with other results (using different methods) for the preparation phase (Volberg & Hubner, 2007) and for congruent stimuli (Malinowski et aI., 2002).…”

EEG alpha oscillations in the preparation for global and local processing predict behavioral performance

“…For example, in their spatial cueing studies Thut et al [2006] used a 50 ms cue plus 2560 ms cue-stimulus interval (52610 ms SOA), and Rihs et al [2007] had a 80 1 1300 5 1380 ms SOA. However, since the focus of this study is on hierarchical processing, the SOA were adopted from other global/local studies [e.g., 600 ms in Volberg and Hü bner, 2007; 800 ms in Yamaguchi et al, 2000; 900 ms in Volberg and Hü bner, 2004].…”

“…For the statistical analysis, the percentaged signal change of alpha levels were averaged within four homologous left-and right-hemispheric electrode clusters (temporo-parietal left: C5/CP5/TP7, temporo-parietal right: C6/CP6/TP8; centroparietal left: CP1/CP3/C3, centro-parietal right: CP2/CP4/ C4; parietal left: P1/P3/P5, parietal right: P2/P4/P6; occipital left: O1/PO3/PO7, occipital right: O2/PO4/PO8). They correspond to those used in Volberg and Hü bner [2007] or in Yamaguchi et al [2000] where four medial and lateral electrode clusters were defined posterior to the central line. Separate analyses were performed for the four homologous clusters.…”

“…The brain mechanisms associated with global/local attentional orienting were also directly addressed in a recent fMRI study [Weissman and Woldorff, 2005; see also Volberg and Hü bner, 2007;Yamaguchi et al, 2000]. The authors presented an informative pre-cue (letter ''G'' for the global level, letter ''L'' for the local level) and measured the brain activity in the interval between cue and target stimulus presentation.…”