1. ATTENTIONAL LAPSES AFFECT AUDITORY P2 AMPLITUDE Introduction It is well known, that even in optimal conditions animals and humans make spontaneous errors which comprise visible behavioral manifestations of attentional failures. In spite of the fact that such errors sometimes lead to negative consequences in professional and everyday activity, the principles and mechanisms of such attention lapses have not been fully understood yet. The technique of evoked potentials has often been applied to the study of attentional lapses (Thomas et al., 2009; Cranford et al., 2004; Benikos et al., 2012). Tasks described in literature usually use distractors or competing tasks, which make participants distract their attention from the target stimuli (“induced” errors). The current study was designed to investigate spontaneous errors made by participants in the absence of any distractors or any overt competing tasks. We have developed a new sustained attention task based on feature conjunction, which creates a moderately high attentional load (Chernyshev et al., 2012). Our goal was to reveal changes in the auditory evoked potentials during spontaneous attentional lapses. Materials and methods Data were obtained in 30 participants (mean age 20.9±1.3 years). Participants were presented with four brief tones (40 ms, 85 dB) which were randomly presented with equal probability. The stimuli could be discriminated by way of conjunction of two distinct features: pitch and noisiness (high pure, high noised, low pure and low noised sounds). Participants were asked to discriminate the stimuli and to respond by pushing one of the two buttons. We asked to push the left button if the participant heard high pure or low noised sound, and to push the right button to high noised or low pure sound (see table). The stimuli used had well discernable differences in their physical characteristics. Task performance required the conjunction of the two physical features, thus imposing a high load on attention (Treisman, Gelade, 1980). Each participant was recorded during 5 blocks of trials, each block consisted of 100 trials. Interstimulus interval was 2500 ms±500 ms. A behavioral outcome could be a correct response, an error or an omission of the response. Evoked potentials were averaged for each type of response separately. Mean prestimulus alpha-(7-12 Hz) power across parietal (P3, Pz, P4) and occipital (O1, Oz, O2) sites was also calculated for each condition. Several prestimulus autonomic system activity indexes (RR-intervals, GSR) were also analyzed. PureNoised HighLeft buttonRight button LowRight buttonLeft button Table. Response contingencies in the experimental task: this table was read as well as handed in printed form to the participants immediately before the experiment. Results Conclusions Mean prestimulus alpha-power, heart rate and N1 amplitude were constant in all three behavioral states; phasic GSR was significantly stronger before errors and omissions compared to correct responses. Thus, failures in the behavioral response were not likely to be caused by reduced arousal level. Since the participants apparently had no difficulties in understanding the response rules and in recognizing the stimuli, the behavioral lapses could be hypothetically explained by reallocation of attentional resources to some covert activity such as mind-wandering, or task-unrelated thoughts (Smallwood et al., 2008), which competed for resources with the processes of sensory information processing and decision making. The role of the P2 peak is not clear at the moment (Tong et al., 2009). According to Melara et al. (2002), P2 is related to discontinuation of ignored information processing. We can speculate that enhanced P2 is a reflection of some processes in the auditory cortex which lead to premature termination of information processing and consequently to failures in the behavioral response. Thus, we consider attentional lapses to be manifestations of signal processing suppression in the sensory areas of the neocortex. References Benikos, N., Johnstone, S. J., Roodenrys, S. J. (2012), ‘Varying task difficulty in the Go/Nogo task: The effects of inhibitory control, arousal, and perceived effort on ERP components’, International Journal of Psychophysiology. 87 (3), 262-272 Chernyshev B.V., Lazarev I.E., Ivanov M.V., Osokina E.S., Vyazovtseva A.A. Аttentional lapses under decision-making: an event-related potential study. Working paper. Series: psychology. WP BRP 06/PSY/2012. Moscow: Higher School of Economics, 2012. URL: http://www.hse.ru/data/2012/12/28/1304052706/06PSY2012.pdf Cranford, J. L., Rothermel, A. K., Walker, L., Stuart, A., Elangovan, S. (2004), ‘Effects of discrimination task difficulty on N1 and P2 components of late auditory evoked potential’, Journal of the American Academy of Audiology, vol. 15, pp. 456-461. Melara, R. D., Rao, A., Tong, Y. (2002). The duality of selection: excitatory and inhibitory processes in auditory selective attention. Journal of experimental psychology. Human perception and performance, 28(2), 279–306. Smallwood J., Beech E.M., Schooler J.W., Handy T.C. (2008). Going AWOL in the brain – mind wandering reduces cortical analysis of the task environment. Journal of Cognitive Neuroscience, 20(3), 458-469. Thomas, S. J., Gonsalvez, C. J., Johnstone, S. J. (2009), ‘Sequence effects in the Go/NoGo task: inhibition and facilitation’, International journal of psychophysiology, vol. 74, pp. 209-219. Tong Y., Melara R. D., Rao A. (2009). P2 enhancement from auditory discrimination training is associated with improved reaction times. Brain Research, 1297, 80–88. Treisman, A. M., Gelade, G. (1980), ‘A feature-integration theory of attention’, Cognitive psychology, vol. 12, pp. 97-136. The study was implemented in the framework of The Basic Research Program of the National Research University Higher School of Economics in 2013. Phasic GSR during prestimulus intervals was significantly greater pronounced in cases of errors or omissions of responses in comparison to correct responses (N=26) Prestimulus heart rate Prestimulus GSR RR-intervals during prestimulus intervals did not differ in cases of correct responses as well as in cases of omissions and errors (N=26) -200-1000100200300400500600 -10 -5 0 5 10 Cz Time, ms Correct responses (N=16) Omissions (N=16) Errors (N=24) Correct responses (N=24) N1 amplitude did not vary upon behavioral outcome P2 amplitude was significantly greater for erroneous responses (F=6.09, p=0.02, N=24) and omissions (F=4.92, p=0.04, N=16) than for correct responses Potential, uV ERP grand average Alpha power during prestimulus intervals did not differ for correct responses, errors and omissions Prestimulus alpha EEG power Lazarev I.E., Chernyshev B.V., Osokina E.S., Vyazovtseva A.A. National Research University Higher School of Economics, Laboratory of Cognitive Psychophysiology, Moscow, Russia ilazarev@hse.ru, bchernyshev@hse.ru For details of ERP results you are welcome to download the working paper at http://www.hse.ru/data/2012/12/28/1304052706/06PSY2012.pdf