Role Of Spatial Attention Research Articles

Spatial Attention in Visual Working Memory Strengthens Feature-Location Binding.

There is a debate about whether working memory (WM) representations are individual features or bound objects. While spatial attention is reported to play a significant role in feature binding, little is known about the role of spatial attention in WM. To address this gap, the current study required participants to maintain multiple items in their WM and employed a memory-driven attention capture paradigm. Spatial attention in WM was manipulated by presenting an exogenous cue at one of the locations that memory items had occupied. The effects of spatial attention on attention guidance in visual search (Experiment 1) and memory performance (Experiments 1 and 2) were explored. The results show that WM-driven attention guidance did not vary based on whether the search features came from the same object in WM; instead, it depended on the number of features, regardless of their source object. In memory tasks, the cued object outperformed the uncued object. Specifically, the test item was better rejected when the features were mis-bound in the cued location than in the uncued location. These findings suggest that memory-driven attention guidance is feature-based, and spatial attention in WM helps bind features into object structures based on location.

The role of spatial attention in crowding and feature binding.

Crowding refers to the failure to identify a peripheral object due to nearby objects (flankers). A hallmark of crowding is inner-outer asymmetry; that is, the outer flanker (more peripheral) produces stronger interference than the inner one. Here, by manipulating attention, we tested the predictions of two competing accounts: the attentional account, which predicts a positive attentional effect on the inner-outer asymmetry (i.e., attention to the outer flanker will increase asymmetry) and the receptive field size account, which predicts a negative attentional effect. In Experiment 1, observers estimated a Gabor target orientation. A peripheral pre-cue drew attention to one of three locations: target, inner flanker, or outer flanker. Probabilistic mixture modeling demonstrated asymmetry by showing that observers often misreported the outer-flanker orientation as the target. Interestingly, the outer cue led to a higher misreport rate of the outer flanker, and the inner cue led to a lower misreport rate of the outer flanker. Experiment 2 tested the effect of crowding and attention on incoherent object reports (i.e., binding errors, reporting the tilt of one presented item with the color of another item). In each trial, observers estimated both the tilt and color of the target. Attention merely increased coherent target reports, but not coherent flanker reports. The results suggest that the locus of spatial attention plays an essential role in crowding, as well as inner-outer asymmetry, and demonstrate that crowding and feature binding are closely related. However, our findings are inconsistent with the view that covert attention automatically binds features together.

Feature-based attention across saccades: Pop-out in color search is spatiotopic.

Our perception of the world remains stable despite the retinal shifts that occur with each saccade. The role of spatial attention in matching pre- to postsaccadic visual information has been well established, but the role of feature-based attention remains unclear. In this study, we examined the transsaccadic processing of a color pop-out target. Participants made a saccade towards a neutral target and performed a search task on a peripheral array presented once the saccade landed. A similar array was presented just before the saccade and we analyzed what aspect of this preview benefitted the postsaccadic search task. We assessed the preview effect in the spatiotopic and retinotopic reference frames, and the potential transfer of feature selectivity across the saccade. In the first experiment, the target and distractor colors remained identical for the preview and the postsaccadic array and performance improved. The largest benefit was observed at the spatiotopic location. In the second experiment, the target and distractor colors were swapped across the saccade. All responses were slowed but the cost was least at the spatiotopic location. Our results show that the preview attracted spatial attention to the target location, which was then remapped, and suggest that previewed features, specifically colors, were transferred across the saccade. Furthermore, the preview induced a spatiotopic advantage regardless of whether the target switched color or not, suggesting that spatiotopy was established independently of feature processing. Our results support independent priming effects of features versus location and underline the role of feature-based selection in visual stability.

Spatial Integration and the Underlying Mechanisms of Cross-Modality Interference.

Researchers have often utilized the classic Stroop task as a measure of selective attention processes. While it is largely agreed upon that semantic interference plays a role in the classic task, the role of attentional processes is less clear. The picture is further muddied when variations on the classic task are used. For example, the cross-modal Stroop task, in which one names the color of visual items while ignoring distracting auditory color words, typically leads to smaller sized interference effects and little or no facilitation when compared to the classic task. Furthermore, relationship(s) with working memory capacity have only been found in the classic version. We examined whether these differences are due to a methodological factor; namely, spatial integration versus separation of the target and distractor locations. We conducted four experiments manipulating the location of auditory distractors within the cross-modal Stroop task, and found that the location of the distractors had little to no impact on the size of the effect. This lack of an effect of location implies that the mechanisms contributing to the cross-modal Stroop effect are not the same as those of the classic Stroop effect, and that the role of spatial attention in cross-modal Stroop is limited. The implications of a unique role for auditory distractors is considered as well, and supports the conclusion that interference in the cross-modal Stroop effect is the result of a combination of semantic interference and modality-specific interference.

Spatial Release From Informational Masking: Evidence From Functional Near Infrared Spectroscopy.

Informational masking (IM) can greatly reduce speech intelligibility, but the neural mechanisms underlying IM are not understood. Binaural differences between target and masker can improve speech perception. In general, improvement in masked speech intelligibility due to provision of spatial cues is called spatial release from masking. Here, we focused on an aspect of spatial release from masking, specifically, the role of spatial attention. We hypothesized that in a situation with IM background sound (a) attention to speech recruits lateral frontal cortex (LFCx) and (b) LFCx activity varies with direction of spatial attention. Using functional near infrared spectroscopy, we assessed LFCx activity bilaterally in normal-hearing listeners. In Experiment 1, two talkers were simultaneously presented. Listeners either attended to the target talker (speech task) or they listened passively to an unintelligible, scrambled version of the acoustic mixture (control task). Target and masker differed in pitch and interaural time difference (ITD). Relative to the passive control, LFCx activity increased during attentive listening. Experiment 2 measured how LFCx activity varied with ITD, by testing listeners on the speech task in Experiment 1, except that talkers either were spatially separated by ITD or colocated. Results show that directing of auditory attention activates LFCx bilaterally. Moreover, right LFCx is recruited more strongly in the spatially separated as compared with colocated configurations. Findings hint that LFCx function contributes to spatial release from masking in situations with IM.

The first letter position effect in visual word recognition: The role of spatial attention.

A prominent question in visual word recognition is whether letters within a word are processed in parallel or in a left to right sequence. Although most contemporary models posit parallel processing, this notion seems at odds with well-established serial position effects in word identification that indicate preferential processing for the initial letter. The present study reports 4 experiments designed to further probe the locus of the first position processing advantage. The paradigm involved masked target words presented for short durations and required participants to subsequently select from 2 alternatives, 1 which was identical to the target and 1 that differed by a single letter. Experiment 1 manipulated the case between the target and the alternatives to ensure that previous evidence for a first position effect was not due to simple perceptual matching. The results continued to yield a robust first position advantage. Experiment 2 attempted to eliminate postperceptual decision processes as the explanatory mechanism by presenting single letters as targets and requiring participants to select an entire word that contained the target letter at different positions. Here the first position advantage was eliminated, suggesting postperceptual decision processes do not underlie the effect. The final 2 experiments presented masked stimuli either all vertically (Experiment 3) or randomly intermixed vertical and horizontal orientation (Experiment 4). In both cases, a robust first position advantage was still obtained. The authors consider alternative interpretations of this effect and suggest that these results are consistent with a rapid deployment of spatial attention to the beginning of a target string which occurs poststimulus onset. (PsycINFO Database Record

Multi-dimensional parietal signals for coordinating attention and decision making

In humans and non-human primates, the parietal lobe plays a key role in spatial attention the ability to extract information from regions of space. This role is thought to be mediated by "priority" maps that highlight attention-worthy locations, and provide top-down feedback for motor orienting and attention allocation. Traditionally, priority signals have been characterized as being purely spatial - i.e., encoding the desired locus of gaze or attention regardless of the context in which the brain generates that selection. Here I argue, however, based on non-spatial modulations found in the monkey lateral intraparietal area, that non-spatial responses are critical for allowing the brain to coordinate attention with action - i.e., to estimate the significance and relative utility of competing sensory cues in the immediate task context. The results prompt an integrative view whereby attention is not a disembodied entity that acts on sensory or motor representations, but an organically emerging process that depends on dynamic interactions within sensorimotor loops. Meeting abstract presented at VSS 2016

Spatial and non-spatial aspects of visual attention: Interactive cognitive mechanisms and neural underpinnings

In humans and non-human primates, the parietal lobe plays a key role in spatial attention – the ability to extract information from regions of space. This role is thought to be mediated by “priority” maps that highlight attention-worthy locations, and provide top-down feedback for motor orienting and attentional allocation. Traditionally, priority signals within the parietal cortex have been characterized as being purely spatial, i.e., encoding the desired locus of gaze or attention regardless of the context in which the brain generates that selection. Here, we highlight evidence from human behavior and neuroimaging as well as monkey physiology, to argue that non-spatial responses are critical to the establishment of priority maps in parietal cortex. This review offers an integrative view of the role that parietal cortex plays in attentional selection, providing evidence that priority maps reflect spatial and non-spatial priorities that ultimately act on sensory information in a spatial way.

When words and space collide: Spatial attention interacts with lexical access during word recognition

ABSTRACTRecent research has suggested an important role for spatial attention in reading, however the nature of this influence is unclear. Further, it has been shown that intention to engage in linguistic processing can enhance lexical processing. Therefore, we developed a novel paradigm to examine the impact of spatial attention on primed and unprimed lexical processing. In a lexical decision task, targets were preceded by a cue to lexical access and spatial location simultaneously. Results indicated that on spatially valid trials, the lexical cuing effect was large and word processing was enhanced, suggesting that spatial attention influences lexical access. On spatially invalid trials, lexical cuing effects were significantly decreased, resulting in a spatial cuing by lexical cuing interaction. Results from this experiment provide evidence that spatial attention interacts with lexical access during word processing. This novel paradigm provides a new avenue for exploring the relations between spatial attention and reading processes.

ID 395 – Effect of transcranial direct stimulation on pseudo-neglect in healthy subjects: Results of a pilot study

Background Subdominant hemispheric lesion results neglect syndrome, where the processing of the visual information coming from the contralateral side is damaged. A similar phenomenon is known in healthy subjects, called pseudo-neglect. In line bisection task there is a tendency to pay more attention to the left side of space. Method We involved 29 healthy subjects. Landmark task was used in a forced choice paradigm to determine the preferred space side. Then cathodal transcranial direct–current stimulation was used in the right region of posterior–parietal cortex. Landmark task was repeated. Fierro score was used to describe the precise choices and the reaction time was calculated. Results 67% of the subjects showed left pseudo-neglect, 22% showed right pseudo-neglect and in 11% pseudo-neglect was not detected. After the stimulation the number of the incorrect choices was increased ( p p p Conclusion Parietal lobe has a crucial role in spatial attention. It can be measured by neurocognitive tests that might serve as a test for the early detection of cognitive impairment. Key message Cathodal stimulation of the parietal lobe can induce a neglect-like symptom.

Distributed attention is implemented through theta-rhythmic gamma modulation

When subjects monitor a single spatial location, target detection depends on the pre-target phase of an ~8 Hz brain rhythm. When multiple locations are monitored, performance decrements suggest a division of the 8 Hz rhythm over the number of locations. This suggests that different locations are sequentially sampled. Indeed, when subjects monitor two locations, performance benefits alternate at a 4 Hz rhythm. These performance alternations followed a reset of attention to one location. Although resets are common and important events for attention, it is unknown, whether in the absence of resets, ongoing attention operates rhythmically. Here, we examined whether spatially specific attentional sampling can be revealed by ongoing pre-target brain rhythms. Specifically, visually induced gamma-band activity plays a role in spatial attention and therefore, we hypothesized that performance can be predicted by a theta-rhythmic gamma modulation. Brain rhythms were assessed with MEG, while subjects monitored bilateral grating stimuli for a unilateral target. The corresponding contralateral gamma-band responses were subtracted from each other to isolate spatially-selective, target-related fluctuations. The resulting lateralized-gamma activity (LGA) showed opposite 4 Hz phases prior to detected versus missed targets. The 4 Hz phase of pre-target LGA accounted for a 14% modulation in performance. These findings suggest that spatial attention is an ongoing theta-rhythmic sampling process, with each sampling cycle implemented through gamma-band synchrony. This extends previous findings by demonstrating that in the case of distributed attention, gamma-band synchrony is shaped by the slower sampling rhythm that governs performance benefits.

Distributed Attention Is Implemented through Theta-Rhythmic Gamma Modulation

When subjects monitor a single location, visual target detection depends on the pre-target phase of an ∼8 Hz brain rhythm. When multiple locations are monitored, performance decrements suggest a division of the 8 Hz rhythm over the number of locations, indicating that different locations are sequentially sampled. Indeed, when subjects monitor two locations, performance benefits alternate at a 4 Hz rhythm. These performance alternations were revealed after a reset of attention to one location. Although resets are common and important events for attention, it is unknown whether, in the absence of resets, ongoing attention samples stimuli in alternation. Here, we examined whether spatially specific attentional sampling can be revealed by ongoing pre-target brain rhythms. Visually induced gamma-band activity plays a role in spatial attention. Therefore, we hypothesized that performance on two simultaneously monitored stimuli can be predicted by a 4 Hz modulation of gamma-band activity. Brain rhythms were assessed with magnetoencephalography (MEG) while subjects monitored bilateral grating stimuli for a unilateral target event. The corresponding contralateral gamma-band responses were subtracted from each other to isolate spatially selective, target-related fluctuations. The resulting lateralized gamma-band activity (LGA) showed opposite pre-target 4 Hz phases for detected versus missed targets. The 4 Hz phase of pre-target LGA accounted for a 14.5% modulation in performance. These findings suggest that spatial attention is a theta-rhythmic sampling process that is continuously ongoing, with each sampling cycle being implemented through gamma-band synchrony.

Conflict resolved: On the role of spatial attention in reading and color naming tasks.

The debate about whether or not visual word recognition requires spatial attention has been marked by a conflict: the results from different tasks yield different conclusions. Experiments in which the primary task is reading based show no evidence that unattended words are processed, whereas when the primary task is color identification, supposedly unattended words do affect processing. However, the color stimuli used to date does not appear to demand as much spatial attention as explicit word reading tasks. We first identify a color stimulus that requires as much spatial attention to identify as does a word. We then demonstrate that when spatial attention is appropriately captured, distractor words in unattended locations do not affect color identification. We conclude that there is no word identification without spatial attention.

Coding dichotomy in lateral intraparietal cortex (LIP) of the macaque monkey and its role in spatial attention

Event Abstract Back to Event Coding dichotomy in lateral intraparietal cortex (LIP) of the macaque monkey and its role in spatial attention Trichur Vidyasagar1*, Ekaterina Levichkina1 and Yuri Saalmann2 1 University of Melbourne, Optometry & Vision Sciences, Australia 2 University of Wisconsin – Madison, Psychology, United States Introduction: Lateral intraparietal cortex (LIP), a part of posterior parietal cortex, is known to be involved in top-down modulation of responses to visual stimuli at earlier stages of the visual pathway1. Many of its neurons show enhancement of responses for stimuli at attended locations and many also show selectivity to the stimulus orientation1. We investigated whether there is a relationship between these two properties in LIP cells, since it has important implications for models of selective attention and the binding problem2. Methods: Two macaques were trained on a delayed match to sample task. They had to match both the location and orientation of two gratings presented with 800 ms delay between them. We measured orientation selectivity of 56 cells in LIP and also the degree of the attentional enhancement in both correct and error trials. Results: Orientation selectivity and attentional enhancement both varied considerably between LIP neurons. However, the cells (N = 25) with significant attentional enhancement (ratio of response to the second presentation of a stimulus at the same location as the first to that of the response to the first stimulus) have significantly lower orientation selectivity (Wilcoxon T-test, p<0.05). Furthermore, the population of attention-selective cells showed around 35% enhancement in correct match trials but only 27% in error trials (Wilcoxon T-test, for the group of 16 cells from sessions with sufficient errors, p<0.05). Conclusion: The results indicate that LIP may be a priority map where salient or preferred spatial locations are selected for further processing, but consequent to a first stage of selection that is sensitive to feature-sensitive inputs. Such an attentional mechanism is ideally suited for detecting targets as in the 2-stage Guided Search model2,3. 1Saalmann YB et al. (2007) Science, 316:1625. 2Vidyasagar TR (1999) Brain Res Rev., 30,66. 3Wolfe JM (1994) Psychonomic Bull. 15, 419. Keywords: macaque, spatial attention, parietal cortex, feature selectivity, guided search Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Attention Citation: Vidyasagar T, Levichkina E and Saalmann Y (2015). Coding dichotomy in lateral intraparietal cortex (LIP) of the macaque monkey and its role in spatial attention. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00381 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Prof. Trichur Vidyasagar, University of Melbourne, Optometry & Vision Sciences, Melbourne, Australia, trv@unimelb.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Trichur Vidyasagar Ekaterina Levichkina Yuri Saalmann Google Trichur Vidyasagar Ekaterina Levichkina Yuri Saalmann Google Scholar Trichur Vidyasagar Ekaterina Levichkina Yuri Saalmann PubMed Trichur Vidyasagar Ekaterina Levichkina Yuri Saalmann Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Strategies of the honeybee Apis mellifera during visual search for vertical targets presented at various heights: a role for spatial attention?

When honeybees are presented with a colour discrimination task, they tend to choose swiftly and accurately when objects are presented in the ventral part of their frontal visual field. In contrast, poor performance is observed when objects appear in the dorsal part. Here we investigate if this asymmetry is caused by fixed search patterns or if bees can use alternative search mechanisms such as spatial attention, which allows flexible focusing on different areas of the visual field.We asked individual honeybees to choose an orange rewarded target among blue distractors. Target and distractors were presented in the ventral visual field, the dorsal field or both. Bees presented with targets in the ventral visual field consistently had the highest search efficiency, with rapid decisions, high accuracy and direct flight paths. In contrast, search performance for dorsally located targets was inaccurate and slow at the beginning of the test phase, but bees increased their search performance significantly after a few learning trials: they found the target faster, made fewer errors and flew in a straight line towards the target. However, bees needed thrice as long to improve the search for a dorsally located target when the target’s position changed randomly between the ventral and the dorsal visual field. We propose that honeybees form expectations of the location of the target’s appearance and adapt their search strategy accordingly. Different possible mechanisms of this behavioural adaptation are discussed.

Strategies of the honeybee Apis mellifera during visual search for vertical targets presented at various heights: a role for spatial attention?

When honeybees are presented with a colour discrimination task, they tend to choose swiftly and accurately when objects are presented in the ventral part of their frontal visual field. In contrast, poor performance is observed when objects appear in the dorsal part. Here we investigate if this asymmetry is caused by fixed search patterns or if bees can use alternative search mechanisms such as spatial attention, which allows flexible focusing on different areas of the visual field. We asked individual honeybees to choose an orange rewarded target among blue distractors. Target and distractors were presented in the ventral visual field, the dorsal field or both. Bees presented with targets in the ventral visual field consistently had the highest search efficiency, with rapid decisions, high accuracy and direct flight paths. In contrast, search performance for dorsally located targets was inaccurate and slow at the beginning of the test phase, but bees increased their search performance significantly after a few learning trials: they found the target faster, made fewer errors and flew in a straight line towards the target. However, bees needed thrice as long to improve the search for a dorsally located target when the target's position changed randomly between the ventral and the dorsal visual field. We propose that honeybees form expectations of the location of the target's appearance and adapt their search strategy accordingly. Different possible mechanisms of this behavioural adaptation are discussed.

Subcortical connections of area V4 in the macaque.

Area V4 has numerous, topographically organized connections with multiple cortical areas, some of which are important for spatially organized visual processing, and others which seem important for spatial attention. Although the topographic organization of V4’s connections with other cortical areas has been established, the detailed topography of its connections with subcortical areas is unclear. We therefore injected retrograde and anterograde tracers in different topographical regions of V4 in nine macaques to determine the organization of its subcortical connections. The injection sites included representations ranging from the fovea to far peripheral eccentricities in both the upper and lower visual fields. The topographically organized connections of V4 included bidirectional connections with four subdivisions of the pulvinar, two subdivisions of the claustrum, and the interlaminar portions of the lateral geniculate nucleus, and efferent projections to the superficial and intermediate layers of the superior colliculus, the thalamic reticular nucleus, and the caudate nucleus. All of these structures have a possible role in spatial attention. The nontopographic, or converging, connections included bidirectional connections with the lateral nucleus of the amygdala, afferent inputs from the dorsal raphe, median raphe, locus coeruleus, ventral tegmentum and nucleus basalis of Meynert, and efferent projections to the putamen. Any role of these structures in attention may be less spatially specific. J. Comp. Neurol. 522:1941–1965, 2014.

Functional Clustering of the Human Inferior Parietal Lobule by Whole-Brain Connectivity Mapping of Resting-State Functional Magnetic Resonance Imaging Signals

The human inferior parietal lobule (IPL) comprised the lateral bank of the intraparietal sulcus, angular gyrus, and supramarginal gyrus, defined on the basis of anatomical landmarks and cytoarchitectural organization of neurons. However, it is not clear as to whether the three areas represent functional subregions within the IPL. For instance, imaging studies frequently identified clusters of activities that cut across areal boundaries. Here, we used resting-state functional magnetic resonance imaging (fMRI) data to examine how individual voxels within the IPL are best clustered according to their connectivity to the whole brain. The results identified a best estimate of seven clusters that are hierarchically arranged as the anterior, middle, and posterior subregions. The anterior, middle, and posterior IPL are each significantly connected to the somatomotor areas, superior/middle/inferior frontal gyri, and regions of the default mode network. This functional segregation is supported by recent cytoarchitechtonics and tractography studies. IPL showed hemispheric differences in connectivity that accord with a predominantly left parietal role in tool use and language processing and a right parietal role in spatial attention and mathematical cognition. The functional clusters may also provide a more parsimonious and perhaps even accurate account of regional activations of the IPL during a variety of cognitive challenges, as reported in earlier fMRI studies.

Local cholinergic interneurons modulate GABAergic inhibition in the chicken optic tectum

The chicken optic tectum (TeO) and its mammalian counterpart, the superior colliculus, are important sensory integration centers. Multimodal information is represented in a topographic map, which plays a role in spatial attention and orientation movements. The TeO is organised in 15 layers with clear input and output regions, and further interconnected with the isthmic nuclei (NI), which modulate the response in a winner-takes-all fashion. While many studies have analysed tectal cell types and their modulation from the isthmic system physiologically, little is known about local network activity and its modulation in the tectum. We have recently shown with voltage-sensitive dye imaging that electrical stimulation of the retinorecipient layers results in a stereotypic response, which is under inhibitory control [S. Weigel & H. Luksch (2012) J. Neurophysiol., 107, 640-648]. Here, we analysed the contribution of acetylcholine (ACh) and the NI to evoked tectal responses using a pharmacological approach in a midbrain slice preparation. Application of the nicotinic ACh receptor (AChR) antagonist curarine increased the tectal response in amplitude, duration and lateral extent. This effect was similar but less pronounced when γ-aminobutyric acid(A) receptors were blocked, indicating interaction of inhibitory and cholinergic neurons. The muscarinic AChR antagonist atropine did not change the response pattern. Removal of the NI, which are thought to be the major source of cholinergic input to the TeO, reduced the response only slightly and did not result in a disinhibition. Based on the data presented here and the neuroanatomical literature of the avian TeO, we propose a model of the underlying local circuitry.

The role of spatial attention during spatial encoding

In the present fMRI study, we aimed to assess whether spatial encoding is mediated by spatial attention. During encoding, participants were presented with abstract shapes to the left or right of fixation. During retrieval, old and new shapes were presented at fixation and participants classified each shape as “old-left”, “old-right”, or “new”. Subsequently remembered items were assumed to have been attended during encoding, while subsequently forgotten items were assumed to have been unattended during encoding. Mirroring classic spatial attention contralateral extrastriate effects, contralateral subsequent memory effects were observed in extrastriate cortical regions BA18 and BA19 (e.g., encoding-left-hits > encoding-left-misses activated the right extrastriate cortex). An additional individual-trial modeling procedure revealed that 79.35% and 100% of accurately encoded items in the left hemisphere and the right hemisphere, respectively, reflected spatial processing. These results suggest that spatial encoding is largely, but not completely, mediated by spatial attention.