Academic journal article Attention, Perception and Psychophysics

Sensitivity of Event-Related Brain Potentials to Task Rules

Academic journal article Attention, Perception and Psychophysics

Sensitivity of Event-Related Brain Potentials to Task Rules

Article excerpt

Published online: 15 May 2012

(C) Psychonomic Society, Inc. 2012

Abstract Previous studies have suggested that brain potentials evoked around 300 ms after stimulus onset index the processes underlying perceptual decision-making. However, the sensitivity of these evoked potentials to the task rules, which link sensory perception to the proper action, has not been studied previously. In this study, event-related potentials (ERPs) of the human brain were examined when subjects randomly performed delayed-matching-to-identity (DMI) and delayed-matching-to-category (DMC) tasks. The results showed that the amplitudes of the brain potentials evoked 228-328 ms after test-stimulus onset varied according to the task rules and indexed the processes responsible for decision-making. In contrast to these potentials, the preceding evoked activity (< 228 ms) did not show any sensitivity to the changes in the subjects' responses and indexed the processes responsible for stimulus perception. These findings support the idea that the potentials evoked after 228 ms from stimulus onset are influenced by the task rules and do not index simple sensory perception.

Keywords Decision-making * Object Recognition * Perceptual categorization and identification * Sensory perception * Visual matching

Decision-making is generally regarded as a series of mental processes resulting in the selection of an action (among different options) on the basis of the available information, including sensory input, internal states, and most importantly, the rules of the task in which a person is engaged. During the past three decades, many studies have examined the neural correlates of decision-making in human and nonhuman primates (for reviews, see Gold & Shadlen, 2007; Heekeren, Marrett, & Ungerleider, 2008). Recent neuroimaging studies have suggested that a domain-general mechanism of decision-making can be responsible for gathering and comparing sensory information and selecting the proper action, independent of the domain of the sensory input and the type of motor output (Heekeren, Marrett, Bandettini, & Ungerleider, 2004; Heekeren, Marrett, Ruff, Bandettini, & Ungerleider, 2006; Ho, Brown, & Serences, 2009; Kayser, Buchsbaum, Erickson, & D'Esposito, 2010). In parallel, studies of event-related potentials (ERPs) have shown that the neural processes underlying decision-making are linked to the late ERP, usually evoked around 300 ms after stimulus presentation within fronto-parietal electrode sites (Bankó, Gál, Kórtvélyes, Kovács, & Vidnyánszky, 2011; Philiastides & Sajda, 2006).

To detect those processes that can be influenced by decision-making processes, previous studies have searched for ERP components whose variations in amplitude (or timing) are correlated to the level of task difficulty and/or to response accuracy (e.g., Bankó et al., 2011; Philiastides & Sajda, 2006). These studies have shown that the amplitudes of ERPs usually evoked around 300 ms after stimulus onset show a strong correlation to response accuracy, while this correlation is weaker, and usually nonsignificant, for earlier components (Bankó et al., 2011; Philiastides & Sajda, 2006).

The other major difference between the neural processes underlying perception and decision-making is that, while the mechanism of object perception can be "category specific" and can vary from one object category to another, decisionmaking processes seem to be "domain general" and act independently of object categories and/or response mechanisms (Heekeren et al., 2006; Heekeren et al., 2008; Ho et al., 2009). For instance, although early ERP components such as the occipito-temporal N170 (Bentin, Allison, Puce, Perez, & McCarthy, 1996; Botzel, Schulze, & Stodieck, 1995; Itier & Taylor, 2004; Nasr & Esteky, 2009), vertex positive potential (VPP; Jeffreys, 1989, 1993, 1996; Joyce & Rossion, 2005; Nasr & Esteky, 2009), and occipito-temporal N250 (Nasr & Esteky, 2009; Schweinberger, Huddy, & Burton, 2004) show selectivity to faces, late components are less sensitive to stimulus category and vary mainly on the basis of task difficulty and/or of the subjects' confidence, irrespective of the test stimulus category (Philiastides & Sajda, 2006). …

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