Hemispheric differences for the integration of stimulus levels and their contents: Evidence from bilateral presentations

Abstract

Several studies have demonstrated that hemispheric differences for the processing of hierarchical letter stimuli are more likely to occur when the letters at the levels are associated with conflicting responses. Typically, a single stimulus is presented, so that the conflict occurs between the global and the local levels of the same stimulus. Our hypothesis is that in this situation, conflict resolution requires integration of the letters and their respective levels and that the hemispheres differ in this integration process. According to this integration theory, the favorable effect of response conflict on hemispheric differences should vanish if other features, such as location, can also serve for conflict resolution. This prediction was tested in the present study by simultaneously presenting an individual hierarchical stimulus to each visual field. Conflicting letters either were arranged within one stimulus or were placed in different stimuli. In the latter case, a response conflict could also be resolved by integrating letters and locations. As was expected, there were no visual field effects in these conditions. On the other hand, visual field effects showed up when the conflicting letters were located within the same stimulus. These results support the idea that the hemispheres differ in their capacity for integrating level and form.

Switching between global and local levels: the level repetition effect and its hemispheric asymmetry

“…These mechanisms probably rely on temporal-parietal areas and play a supervisory role in the attentional control for global/local processing within the prestriate cortex (Yamaguchi et al, 2000). For example, the classical hemispheric asymmetries for global/local processing are more robust in divided- than focused-attention tasks (Van Kleeck, 1989; Heinze et al, 1998; Yovel et al, 2001), and when solving information conflict between levels is necessary (Hübner and Malinowski, 2002; Malinowski et al, 2002; Volberg and Hubner, 2004, 2006; Hübner and Volberg, 2005; Hübner et al, 2007). Additionally, hemispheric asymmetries due to the global-local distinction can be obscured by some aspects of the material which may produce co-varying effects due to the involvement of other processes which are also lateralised.…”

Hemispheric differences for global/local processing in divided attention tasks: Further evidence for the integration theory

“…Accounts proposed so far for explaining this difference (Heinze et al, 1998;Yovel et al, 2001) are rather restricted and, therefore, cannot explain our additional results. For instance, in various studies from our group (Hübner, 1997(Hübner, , 1998Hübner & Volberg, 2005;Malinowski et al, 2002;Volberg & Hübner, 2004, 2006, we have demonstrated that VFEs also occur reliably with selective-attention tasks, but only for incongruent stimuli-that is, when global and local information activate competing responses-and mainly when the target level is randomized. This pattern cannot be explained by the current accounts.…”

“…In particular, they cannot explain why response conflict supports the appearance of VFEs in selective-attention tasks Hübner & Volberg, 2005;Van Kleeck, 1989;Volberg & Hübner, 2004, 2006. Therefore, it would be desirable to have a more general theory.…”

“…Thus, an important issue in this field concerns the question of the factors that are responsible for the modulation of hemispheric differences. During the last few years, Hübner and his coworkers (e.g., Hübner, 1997Hübner, , 1998Volberg & Hübner, 2004, 2006 have shown that response conflict is such a factor (see also Van Kleeck, 1989). In a series of studies, they applied a selective-attention task, in which subjects had to indicate the letter at a prespecified level and ignore the letter at the other level.…”

Callosal degradation in HIV-1 infection predicts hierarchical perception: A DTI study

“…We assumed that HIV-1-related impairment in attentional control would be related to compromised integrity in anterior and middle callosal fibers connecting frontal and parietal cortices. Attentional control is required when local and global information is incongruent (i.e., a global E made up from local Ts) (Hibi, Takeda, & Yagi, 2002; Müller-Oehring et al, 2007; Navon, 1977; Proverbio, Minniti, & Zani, 1998) and is associated with conflicting responses (Müller-Oehring et al, 2007; Volberg & Hübner, 2006). Because we had observed earlier (Müller-Oehring et al, 2007, 2009) that redundant target information at both local and global processing levels results in response facilitation, an effect attributable to perceptual preattentive processing (Martin, Sorensen, Robertson, Edelstein, & Chirurgi, 1992, Martin et al, 1995; Sorensen, Martin, & Robertson, 1994; Tzelgov, Henik, & Berger, 1992), we assumed that HIV-1-related impairment in local-global facilitation would be related to compromise in posterior callosal microstructural integrity connecting occipito-temporal visual processing areas.…”