An exploration of varieties of visual attention: ERP findings

Experimental Brain Research, 2007

Lateralised ERP responses were measured over posterior visual brain regions in response to visual search arrays that contained one colour singleton. In the localisation task, responses were determined by the visual hemiWeld where this singleton was presented. In the discrimination task, they were determined by the singletons' shape. While an N2pc component was elicited in an identical fashion in both tasks, a subsequent sustained contralateral negativity was consistently present at posterior sites in the discrimination task only. This dissociation demonstrates that these two activations reXect distinct visual processing stages. We suggest that while the N2pc reXects the ability of the visual system both to identify and localise a relevant stimulus in the scene, the late sustained activity reXects the subsequent in-depth analysis and identiWcation of these stimuli.

Frontiers in Human Neuroscience, 2023

Psychophysiology, 2000

Twenty-eight volunteers were instructed to attend stimuli presented at one side of the computer screen and to ignore stimuli presented at the other side. Both attended and unattended stimulus series consisted of targets~25%! and nontargets~75%! defined on the basis of stimulus shape. Attended targets required a binary choice based on stimulus color. Selective attention led to the expected increase in both midlatency~N2b! and late~P3! brain potential components. Furthermore, selective attention led to increased anticipatory cardiac slowing preceding the target stimulus and to increased primary bradycardia. Correlational analyses revealed a positive relation between the effects of selective attention on N2b amplitude and primary bradycardia suggestive of cortical involvement in the chronotropic control of heart rate. Descriptors: Event-related brain potentials, Heart rate, Visual selective attention, Anterior cingulate cortex Event-related brain potentials~ERPs! have been successfully used to examine the temporal dynamics of selective attention~for reviews, see Harter & Aine, 1984; Wijers, Mulder, Gunter, & Smid, 1996!. The brain potential analysis of visual selective attention identified a number of ERP components that have been interpreted to reflect different levels of selective information processing. For visual selective attention based on spatial location, these ERP components include~a! posterior positivity~P1! peaking between 100 and 160 ms,~b! posterior negativity~N1! peaking between 160 and 210 ms,~c! centrofrontal negativity~N2b! peaking between 200 and 300 ms, and~d! central positivity~P3a! with a maximum between 300 and 500 ms. The P1 and N1 components are specific to spatial selection and have been interpreted to reflect sensory facilitation within the visual system~e.g., Hillyard & Mangun, 1986!. The attention effects on N2b and P3a amplitudes have been observed in a wide variety of selective attention tasks and thus appear to be feature nonspecific. The N2b is believed to reflect an attentional orienting process facilitating a more extensive processing of relevant stimuli, and the P3a is considered to index the selective processing of the stimulus for target properties~e.g.,

2007

Lateralised ERP responses were measured over posterior visual brain regions in response to visual search arrays that contained one colour singleton. In the localisa- tion task, responses were determined by the visual hemiWeld where this singleton was presented. In the discrimination task, they were determined by the single- tons' shape. While an N2pc component was elicited in an identical fashion in both tasks, a subsequent sustained con- tralateral negativity was consistently present at posterior sites in the discrimination task only. This dissociation dem- onstrates that these two activations reXect distinct visual processing stages. We suggest that while the N2pc reXects the ability of the visual system both to identify and localise a relevant stimulus in the scene, the late sustained activity reXects the subsequent in-depth analysis and identiWcation of these stimuli.

Human Brain Mapping, 1998

This study characterized patterns of brain electrical activity associated with selective attention to the color of a stimulus. Multichannel recordings of event-related potentials (ERPs) were obtained while subjects viewed randomized sequences of checkerboards consisting of isoluminant red or blue checks superimposed on a grey background. Stimuli were presented foveally at a rapid rate, and subjects were required to attend to the red or blue checks in separate blocks of trials and to press a button each time they detected a dimmer target stimulus of the attended color. An early negative ERP component with an onset latency of 50 ms was sensitive to stimulus color but was unaffected by the attentional manipulation. ERPs elicited by attended and unattended stimuli began to diverge after approximately 100 ms following stimulus onset. Inverse dipole modelling of the attended-minus-unattended difference waveform indicated that an initial positive deflection with an onset latency of 100 ms had a source in lateral occipital cortex, while a subsequent negative deflection with an onset at 160 ms had a source in inferior occipito-temporal cortex. Longer-latency attention-sensitive components were localized to premotor frontal areas (onset at 190 ms) and to more anterior regions of the fusiform gyrus (onset at 240 ms). These source localizations correspond closely with cortical areas that were identified in previous neuroimaging studies as being involved in color-selective processing. The present ERP data thus provide information about the time course of stimulus selection processes in cortical areas that subserve attention to color. Hum.

Experimental Brain Research, 2008

Brain-based models of visual attention hypothesize that attention-related beneWts aVorded to imperative stimuli occur via enhancement of neural activity associated with relevant spatial and non-spatial features. When relevant information is available in advance of a stimulus, anticipatory deployment processes are likely to facilitate allocation of attention to stimulus properties prior to its arrival. The current study recorded EEG from humans during a centrally-cued covert attention task. Cues indicated relevance of left or right visual Weld locations for an upcoming motion or orientation discrimination. During a 1 s delay between cue and S2, multiple attention-related events occurred at frontal, parietal and occipital electrode sites. DiVerences in anticipatory activity associated with the non-spatial task properties were found late in the delay, while spatially-speciWc modulation of activity occurred during both early and late periods and continued during S2 processing. The magnitude of anticipatory activity preceding the S2 at frontal scalp sites (and not occipital) was predictive of the magnitude of subsequent selective attention eVects on the S2 event-related potentials observed at occipital electrodes. Results support the existence of multiple anticipatory attention-related processes, some with diVering speciWcity for spatial and non-spatial task properties, and the hypothesis that levels of activity in anterior areas are important for eVective control of subsequent S2 selective attention.

Psychophysiology, 2016

Our ability to select task-relevant information from cluttered visual environments is widely believed to be due to our ability to tune attention to the particular elementary feature values of a sought-after target (e.g., red, orange, yellow). By contrast, recent findings showed that attention is often tuned to feature relationships, that is, features that the target has relative to irrelevant features in the context (e.g., redder, yellower). However, the evidence for such a relational account is so far exclusively based on behavioral measures that do not allow a safe inference about early perceptual processes. The present study provides a critical test of the relational account, by measuring an electrophysiological marker in the EEG of participants (N2pc) in response to briefly presented distractors (cues) that could either match the physical features of the target or its relative features. In a first experiment, the target color and nontarget color were kept constant across trials....

International Journal of Psychophysiology, 1998

In a visual discrimination task stimuli consisted of a color circle and a grating pattern, i.e. target features were Ž . distributed between two objects. The relation hierarchical vs. parallel between the attentional processing of the Ž . task-related features color and spatial frequency was investigated by using the methods of event-related potentials Ž . Ž . ERPs . Participants with considerable practice in visual attention target shooters; n s 13 were compared to control Ž . Ž . Ž . subjects n s 11 . Attention-related ERP components, i.e. selection anterior positivity SP , selection negativity Ž .

Biological Psychology, 2012

Numerous studies have demonstrated that selective attention to color is associated with a larger neural response under attend than ignore conditions, but have not addressed whether this difference reflects enhanced activity under attend or suppressed activity under ignore. In this study, a color-neutral condition was included, which presented stimuli physically identical to those under attend and ignore conditions, but in which color was not task relevant. Attention to color did not modulate the early sensory-evoked P1 and N1 components. Traditional ERP markers of early selection (the anterior Selection Positivity and posterior Selection Negativity) did not differ between the attend and neutral conditions, arguing against a mechanism of enhanced activity. However, there were markedly reduced responses under the ignore relative to the neutral condition, consistent with the view that early selection mechanisms reflect suppression of neural activity under the ignore condition.

Proceedings of the National Academy of Sciences, 2006

We used an electrophysiological measure of selective stimulus processing (the steady-state visual evoked potential, SSVEP) to investigate feature-specific attention to color cues. Subjects viewed a display consisting of spatially intermingled red and blue dots that continually shifted their positions at random. The red and blue dots flickered at different frequencies and thereby elicited distinguishable SSVEP signals in the visual cortex. Paying attention selectively to either the red or blue dot population produced an enhanced amplitude of its frequency-tagged SSVEP, which was localized by source modeling to early levels of the visual cortex. A control experiment showed that this selection was based on color rather than flicker frequency cues. This signal amplification of attended color items provides an empirical basis for the rapid identification of feature conjunctions during visual search, as proposed by ''guided search'' models. electrophysiology ͉ feature-based attention ͉ steady-state evoked potential ͉ visual search Author contributions: M.M.M. and P.M. designed research; M.M.M. and S.A. performed research; N.J.T. and P.V.-S. contributed new reagents͞analytic tools; S.A., N.J.T., and P.M. analyzed data; M.M.M. and S.A.H. wrote the paper; and S.A. wrote the stimulation program.

Brain and Cognition, 1998

International Journal of Psychophysiology, 2014

We investigated how target colour affected behavioural and electrophysiological results in a visual search task. Perceptual and attentional mechanisms were tracked using the N2pc component of the event-related potential and other lateralised components. Four colours (red, green, blue, or yellow) were calibrated for each participant for luminance through heterochromatic flicker photometry and equated to the luminance of grey distracters. Each visual display contained 10 circles, 1 colored and 9 grey, each of which contained an oriented line segment. The task required deploying attention to the colored circle, which was either in the left or right visual hemifield. Three lateralised ERP components relative to the side of the lateral coloured circle were examined: a posterior contralateral positivity (Ppc) prior to N2pc, the N2pc, reflecting the deployment of visual spatial attention, and a temporal and contralateral positivity (Ptc) following N2pc. Red or blue stimuli, as compared to green or yellow, had an earlier N2pc. Both the Ppc and Ptc had higher amplitudes to red stimuli, suggesting particular selectivity for red. The results suggest that attention may be deployed to red and blue more quickly than to other colours and suggests special caution when designing ERP experiments involving stimuli in different colours, even when all colours are equiluminant.

Cognitive Brain Research, 2002

The aim of the present study was to investigate the neural mechanisms of stimulus orientation selection in humans by recording event-related potentials (ERPs) of the brain with a 32-channel montage. Stimuli were isoluminant black-and-white gratings (3 cpd) having an orientation of 508, 708, 908, 1108 and 1308, randomly presented in the foveal portion (28 of visual angle) of the central visual field. The task consisted in selectively attending and responding to one of the five grating orientations, while ignoring the others. ERP results showed that orientation selection affected neural processing starting already at an early post-stimulus latency. The P1 component (80-140 ms) measured at temporal area, which might well be reflecting the activity of the ventral stream (i.e. 'WHAT' system) of the visual pathways, showed an enhanced amplitude for target orientations. These effects increased with progressive neural processing over time as reflected by selection negativity (SN) and P300 components. In addition, both reaction times (RTs) and ERPs showed a strong 'oblique' effect, very probably reflecting the perceptual predominance of orthogonal versus oblique stimulus orientation in the human visual system: RTs were much faster, and SN and P300 components much larger, to gratings presented vertically than in other orientations.

Electroencephalography and Clinical Neurophysiology, 1997

The aim of this study was to determine whether the visual frontal processing negativity reported in our earlier paper (Karayanidis, F. and Michie, P.T. Electroenceph. clin. Neurophysiol., 1996, 99: 38-56) is related to selection of spatial location, or occurs regardless of the stimulus features used to define the target. Subjects were instructed to respond to infrequent target stimuli of a particular combination of orientation, color and size. All stimuli were presented at central fixation. Posteriorly, orientation selection enhanced P125 amplitude over the right hemisphere but neither orientation nor color selection had an effect on N190. Posterior selection negativities emerged for orientation, color and their conjunction. At anterior sites, widespread effects of orientation and color processing were evident. The effect of location selection on the anterior Nl seen in our previous study was not evident with orientation selection. Instead, selection of orientation, color and their conjunction resulted in PI455250 frontally. Two later anterior negativities emerged. The early negativity (vPNe) was affected independently by orientation and color selection while the late negativity (vPN1) was affected only by selection of feature conjunction. Thus, the present results show that, like its auditory counterpart, the visual processing negativity occurs with a variety of stimulus classification features and is not exclusively related to spatial selection. 0 1997 Elsevier Science Ireland Ltd.

Psychophysiology, 2006

It is often assumed that when a neutral cue is presented in a spatial cueing task, attention remains at fixation until target onset. We hypothesized that variance in nonspatial attention and switches of attention toward target locations can account for variance in reaction times of neutral trials. Lateralized event-related potentials (ERPs) and changes in electroencephalogram (EEG) frequency bands served as predictor variables in a single-trial logistic regression analysis to predict the direction of spatial attention in cued and neutral trials. The contingent negative variation (CNV) and nonlateralized changes in the alpha band served as markers of nonspatial attention. The direction of attention in cued trials was reliably predicted from single-trial lateralized ERP components. In neutral trials, only evidence for nonspatial attention was found, indicated by increases in the CNV and decreases in alpha preceding targets to which responses were relatively fast.