Object-related Attention: An Event-related Potential Study

Perception & Psychophysics, 1990

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.

Biological Psychology, 1999

Two experiments were performed in which the effects of selective spatial attention on the ERPs elicited by unilateral and bilateral stimulus arrays were compared. In Experiment 1, subjects received a series of grating patterns. In the unilateral condition these gratings were presented one at a time, randomly to the right or left of fixation. In the bilateral condition, gratings were presented in pairs, one to each side of fixation. In the unilateral condition standard ERP effects of visual spatial attention were observed. However, in the bilateral condition we failed to observe an attention related posterior contralateral positivity (overlapping the P1 and N1 components, latency interval about 100 -250 ms), as reported in several previous studies. In Experiment 2, we investigated whether attention related ERP lateralizations are affected by the task requirement to search among multiple objects in the visual field. We employed a task paradigm identical to that used by Luck et al. (Luck, S.J., Heinze, H.J., Mangun, G.R., Hillyard, S.A., 1990. Visual event-related potentials index focused attention within bilateral stimulus arrays. II. Functional dissociation of P1 and N1 components. Electroencephalogr. Clin. Neurophysiol. 75, 528 -542). Four letters were presented to a visual hemifield, simultaneously to both the attended and unattended hemifields in the bilateral conditions, and to one hemifield only in the unilateral conditions. In a focused attention condition, subjects searched for a target letter at a fixed position, whereas they address: [email protected] (A.A. Wijers) 0301-0511/99/$ -see front matter © 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 1 -0 5 1 1 ( 9 9 ) 0 0 0 0 9 -5 J.J. Lange et al. / Biological Psychology 50 (1999) 203-233 204 searched for the target letter among all four letters in the divided attention condition (as in the experiment of . In the bilateral focused attention condition, only the contralateral P1 was enhanced. In the bilateral divided attention condition a prolonged posterior positivity was observed over the hemisphere contralateral to the attended hemifield, comparable to the results of . A comparison of the ERPs elicited in the focused and divided attention conditions revealed a prolonged 'search related negativity'. We discuss possible interactions between this negativity and attention related lateralizations. The display search negativity consisted of two phases, one phase comprised a midline occipital negativity, developing first over the ipsilateral scalp, while the second phase involved two symmetrical occipitotemporal negativities, strongly resembling the N1 in their topography. The display search effect could be modelled with a dipole in a medial occipital (possibly striate) region and two symmetrical dipoles in occipitotemporal brain areas. We hypothesize that this effect reflects a process of rechecking the decaying information of iconic memory in the occipitotemporal object recognition pathway.

International Journal of Psychophysiology, 1993

Sokolov's (1963) model-comparator theory of orienting and attention theorizes that different events underlie passive and active processing of sensory information presented in different contexts. The following study investigates changes in event-related potentials (ERPs) related to this theory by presenting stimuli inter-and intra-modally during passive and active processing tasks. Model-comparator theory proposes that novel events are detected by a mismatch discrimination process made between incoming and previously presented stimuli during preattentive processing. Central processing is engaged when this mismatch is relevant to the organism. To explore how engaging central processing, induced by instructional priming, affects preattentive processing, a 'truly' passive task was compared with a standard active task. This 'truly' passive task is different from the distracted one normally used to control direction of attention in ERP experiments in that it did not instruct subjects attention towards any task. ERP data were modeled as a dipole whose trajectory moved through voltage space. Our results suggest that both the spatial components and the magnitude of the dipole trajectory changed as functions of both passive and active processing and the context in which stimuli were presented. Our results also suggest that the trajectory and magnitudes of certain ERP components reflect processes proposed by model-comparator theory.

Attention, perception & psychophysics, 2015

Attention may select objects or perceptual groups as fundamental units. Previous studies with event-related potentials (ERPs) have found that obligatory attention-spreading over spatial regions within stable objects is associated with intermediate feedforward visual processing, as reflected by the posterior N1 component of the ERP at a latency of 140-180 ms. The present study examined object-based spatial attention effects in response to individual objects, by recording lateralized ERP attention effects over the posterior scalp (i.e., contralateral versus ipsilateral to the attended visual fields). The stumuli were bilateral unfilled line objects with minimal figural enhancement, and their connectedness and the difficulty of the perceptual task were manipulated. The effects of spatial attention on successive ERP components (N1, P2, and N2) provided information on the timing of the different stages of processing that underlie the formation of perceptual objects.

Brain Research Bulletin, 1995

In our previous studies, we have demonstrated an ERP correlate of visual memory with a modified delayed matching-to-sample paradigm using a series of nonsense line drawings or faces as stimuli. In this experiment, we employed pictures of objects to determine whether the ERP can reflect the object recognition process and whether visual stimuli with a verbal label would result in a different topographic distribution from past topography obtained with visual stimuli without a verbal label. The results of this study suggest that the amplitude of the ERP component (c247) to repeated (primed) pictures of common objects was significantly decreased as compared to the unrepeated (unprimed) pictures; the latency for the peak of c247 was decreased for the repeated compared to the unrepeated, and the response time was also significantly shorter to the repeated picture stimuli than to the unrepeated; the topographical distribution of c247 was mainly located in the occipitotemporal areas of the brain. However, the source energy density map showed that the topographic involvement of the brain regions to the c247 was different in the matching and nonmatching trials.

Electroencephalography and Clinical Neurophysiology, 1995

In ERP literature on visual selective attention evidence has been provided that selectively directing attention to a spatial frequency affects the visual processing of the attended frequency, and of unattended frequencies within the same channel bandwidth, starting at a relatively late level of post-stimulus processing, i.e., after about 150 msec. Nevertheless, little knowledge is available about the topographic distribution of these attention effects. This study investigated attentional selection of stimulus relative size at occipital and latero-occipital sites, as well as at fronto-lateral sites.

Acta Psychologica, 1985

Neuroimage, 2004

Biological Psychology, 1998

Event-related potentials (ERPs) were recorded to trains of rapidly presented auditory and visual stimuli. ERPs in conditions in which subjects attended to different features of visual stimuli were compared with ERPs to the same type of stimuli when subjects attended to different features of auditory stimuli. This design permitted us to study effects of variations in both intramodal and intermodal visual attention on the timing and topography of ERP components in the same experiment. There were no indications that exogenous N110, P140 and N180 components to line gratings of high and low spatial frequencies were modulated by either intra-or intermodal forms of attention. Furthermore, intramodal and intermodal attention effects on ERPs showed similar topographical distributions. These combined findings suggest that the same neural generators in extrastriate occipital areas are involved in both forms of attention. Visual ERPs elicited in the condition in which subjects were engaged in auditory selective attention showed a large positive displacement at the occipital scalp sites relative to ERPs to attended and unattended stimuli in the visual condition. The early onset of this positivity might be associated with a highly confident and early rejection of the irrelevant visual stimuli, when these stimuli are presented among auditory stimuli. In addition, the later onset of selection potentials in the intramodal condition suggests that a more precise stimulus selection is needed when features of visual stimuli are rejected among other features of the same stimulus pattern, than when visual stimuli are rejected among stimuli of another modality.