Abstract

Mismatch negativity (MMN) has been characterised as a ‘pre-attentive’ component of an event-related potential (ERP) that is related to discrimination and error prediction processes. The aim of the current experiment was to establish whether visual MMN could be recorded to briefly presented, backward and forward masked visual stimuli, given both below and above levels of subjective experience. Evidence of visual MMN elicitation in the absence of the ability to consciously report stimuli would provide strong evidence for the automaticity of the visual MMN mechanism. Using an oddball paradigm, two stimuli that differed in orientation from each other, a + and an ×, were presented on a computer screen. Electroencephalogram (EEG) was recorded from nine participants (six females), mean age 21.4 years. Results showed that for stimuli that were effectively masked at 7 ms presentation, there was little variation in the ERPs evoked to standard and deviant stimuli or in the subtraction waveform employed to delineate the visual MMN. At 14 ms stimulus presentation, when participants were able to report stimulus presence, an enhanced negativity at around 175 and 305 ms was observed to the deviant and was evident in the subtraction waveform. However, some of the difference observed in the ERPs can be attributed to stimulus characteristics, as the use of a ‘lonely’ deviant protocol revealed attenuated visual MMN components at 14 ms stimulus presentation. Overall, results suggest that some degree of conscious attention is required before visual MMN components emerge, suggesting visual MMN is not an entirely pre-attentive process.

Highlights

  • The automatic detection of change in the visual environment is key to human survival and adaptive behaviour

  • Visual inspection of the grand average waveforms reveals an enhanced negativity in the event-related potential (ERP) response to the deviant when stimuli were presented for 14 ms, with a maximal difference at approximately 175 ms and at around 305 ms compared to the standard stimuli

  • The results of this study show that for stimuli that were not reportable using the backward and forward masking paradigm employed, i.e. those presented at 7 ms, there was little variation in the ERPs evoked to standard and deviant stimuli

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Summary

Introduction

The automatic detection of change in the visual environment is key to human survival and adaptive behaviour. The mechanisms for detecting changes in the absence of focal attention are beginning to be understood. It is assumed that rather than passively registering environmental regularities the brain actively predicts the causes of sensory inputs (Friston 2005, 2010; Rao and Ballard 1999). Within this framework, sensory input entering the primary visual cortex is actively compared with top–down predictions and the MMN is elicited when there is a failure to suppress error prediction (Friston 2005; Garrido et al 2009). For a review of MMN studies interpreted within this framework see Stefanics et al (2014); Winkler and Czigler (2012)

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