A direct comparison of exogenous and endogenous inhibition of return and selective attention mechanisms in the somatosensory system

Abstract

The interaction of excitation and inhibition in responses due to attentional mechanisms in the visual system has been investigated. The studies reported herein use the tactile system of humans to test a specific hypothesis about the processes of attention that have never been directly addressed. Both exogenous and endogenous Inhibition of Return (IOR) reaction-time paradigms with a 100 Hz, 35 microm of peak displacement amplitude were used. In these experiments multiple Stimulus Onset Asynchronies were tested which made it difficult for subjects to learn timing patterns. We tested whether a detection time to a target which is to be attended to is a composite of at least two underlying mechanisms. These mechanisms were explored using exogenous and endogenous IOR experiments. It is hypothesized that these mechanisms work in a push-pull fashion: one deploying attention when new events occur, and the other withdrawing attention ("Disengagement") after it has been deployed. Based on the results, a new hypothesis is proposed stating that one form of attention (selective attention) competes with IOR in determining the time taken to detect a target in the tactile system.

Reflexive attention in touch: An investigation of event related potentials and behavioural responses

“…Attention research has traditionally focused on the visual In line with previous studies on exogenous tactile attention we 496 found IOR in the detection task (Cohen et al, 2005;Lloyd et al, 497 1999;Poliakoff et al, 2002;Röder et al, 2000Röder et al, , 2002; that is,…”

“…(for review see Klein, 2000), auditory (Schmidt, 1996; Tassinari 37 and Berlucchi, 1995), tactile modality (Cohen et al, 2005; Lloyd 38 et al, 1999; Poliakoff et al, 2002; Röder et al, 2000 Röder et al, , 2002, and SOA is used whilst IOR occurs at a cue-target interval of 1000 ms. …”

Independent effects of endogenous and exogenous attention in touch

“…Typically in such a cue-target paradigm endogenous attention would be induced by an informative central cue indicating the most likely location for an upcoming peripheral target. Endogenous orienting generally leads to enhanced processing for targets at attended locations with facilitation of response times (RTs) (e.g., Müller & Rabbitt, 1989;Cohen, Bolanowski, & Verrillo, 2005). Exogenous orienting in a Posner paradigm would be induced by presenting non-informative peripheral cues.…”

“…Furthermore, most studies investigating tactile attention have not controlled for visual orienting effects on tactile processing. A number of tactile attention studies have used visual cues to direct attention to tactile targets (Chica et al, 2007;Forster & Eimer, 2005;Posner, 1978;Spence, Pavani, & Driver, 2000) inducing crossmodal orienting effects (Chica et al, 2007;Mondor & Amirault, 1998;Turatto, Benso, Galfano, & Umilta, 2002), while in other studies (e.g., Cohen et al, 2005;Lloyd et al, 1999) participants moved their eyes to the tactile target location inducing visual overt orienting effects (Rorden, Greene, Sasine, & Baylis, 2002). Other cross-modal paradigms have investigated the automaticity of exogenous tactile stimuli by varying visual perceptual load.…”

“…To understand the operations of tactile attentional mechanisms and to clarify whether attentional mechanisms are modality specific or operate in the same fashion across modalities, tactile attention studies employing modality specific paradigms (e.g., employing tactile cues and targets) and excluding engagement of other modalities (e.g., vision) are required. Endogenous and exogenous attention has been researched with purely tactile cues and targets and IOR has been demonstrated in touch (Cohen, et al, 2005;Lloyd et al, 1999;Poliakoff et al, 2002;Röder, Spence, & Rösler, 2002;Röder, Spence, & Rösler, 2000, Jones & Forster, 2012.…”