Uncued Object 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 flickering spotlight of visual attention: Characterizing abnormal object-based attention in schizophrenia

Schizophrenia is associated with deficits in both object perception and visual attention. However, few studies in schizophrenia have investigated object-based attention, which is dissociable from other forms of visuospatial attention. Recent research in healthy populations has shown that the ‘spotlight’ of sustained visual attention flickers in a rhythmic, oscillatory fashion at specific frequencies in the 4-12 Hz range. In healthy samples, this oscillatory signature has been used to investigate spatiotemporal dynamics of object-based attention, showing that the attentional spotlight spreads to uncued locations within cued objects, and also periodically alternates focus between cued and uncued objects. In this study, we adapted a performance-based visual object cueing task to investigate object-based attention in individuals with a schizophrenia diagnosis and healthy controls. In controls, spatiotemporal patterns of object-based attention closely resembled those reported in previous studies of healthy individuals. In the schizophrenia group, the oscillatory signature of attention also appeared in the location of the cue and on uncued objects, similar to the effects in controls. Indeed, the oscillatory signature of attention at the spatial location of the cue was stronger in the schizophrenia group than in controls. However, attention did not spread across the cued object in schizophrenia; rather, attention appeared to remain hyperfocused at the spatial location of the cue. These findings provide the first evidence that visual attention has oscillatory characteristics in schizophrenia, as in the general population. The results also show that the fundamental process of attentional spreading which underlies object-based attention is abnormal in schizophrenia.

Neural evidence for the impact of facial trustworthiness on object processing in a gaze-cueing task in 7-month-old infants

ABSTRACTHumans automatically judge a person’s trustworthiness solely based on facial features and use these judgments to inform subsequent behavior. While recent studies demonstrate that already infants are sensitive to variance in facial trustworthiness, it remains unclear whether this variance also influences subsequent socio-cognitive processes. We investigated event-related brain responses (ERPs) to faces varying in trustworthiness in a gaze-cueing paradigm in 7-month-old infants. Our analysis focused on the ERP responses to cued or un-cued objects shown in isolation after the gaze-cue was presented. We observed an enhanced occipital positive slow wave (PSW) to un-cued compared to cued objects, suggesting a gaze-cueing effect irrespective of facial trustworthiness. Furthermore, objects in the un-cued condition elicited a larger fronto-central Nc when the gaze cue was provided by trustworthy compared to untrustworthy faces. This pattern suggests that while gaze cueing occurs irrespective of facial trustworthiness, allocation of attention, as indexed by modulation of the Nc amplitude, varies as a function of trustworthiness. Taken together, our results show that facial trustworthiness impacts object processing in the context of a gaze cueing paradigm, adding to the notion that it serves as an important social cue from early in ontogeny.

Gaze cues of isolated eyes facilitate the encoding and further processing of objects in 4-month-old infants

We investigated young infants’ object encoding and processing in response to isolated eye gaze cues on the neural and behavioral level. In two experiments, 4-month-old infants watched a pair of isolated eyes gazing towards or away from novel objects. Subsequently, the same objects were presented alone (i.e., without eyes). We measured event-related potentials (ERP) in response to object-directed and object-averted eye gaze as well as to the subsequently presented isolated objects. Using eye-tracking methods, we additionally measured infants’ looking behavior in reaction to the subsequently presented isolated objects. The ERP data revealed an enhanced slow wave positivity for object-directed eye gaze, indicating increased encoding of observed gaze cues. Regarding the objects, we found an enhanced Nc amplitude and increased looking times in response to previously uncued objects, indicating a novelty response on the neural and behavioral level. The results suggest that isolated eye gaze stimuli are sufficient to trigger object encoding and facilitate further object processing.

The development of object-based attention in infants

We examined whether infants aged 6–8 months show object-based attention using the preferential looking method. In object-based attention, which is a prerequisite function for efficient real-world processing of various stimuli, a target that appears at a cued object is detected and processed faster than a target appearing at an uncued object. We presented 6- to 8-month-old infants with the visual stimuli consisting of two white vertical rectangles side by side, in which a target appearing at 1) the cued location, 2) the end opposite to the cued location, and 3) another rectangle’s end following the cue, using an established paradigm, and measured each infant’s first saccade to the target. We found that (1) infants of all ages could make the first saccade to the target appearing at the cued location, (2) only 8-month-old infants made the first saccade to the target appearing at the opposite end to the cued location more accurately than to the target appearing at the other rectangle’s end. These results indicate that object-based attention might be acquired around 8 months compared with the spatial cueing effect that appears at around 6 months. Our findings suggest that the objects play a role in visual attention in 8-month-old infants.

Occipital, parietal, and frontal cortices selectively maintain task-relevant features of multi-feature objects in visual working memory

Previous studies have shown that information held in visual working memory is represented in the occipital, parietal, and frontal cortices. However, less is known about whether the mnemonic information of multi-feature objects is modulated by task demand in the parietal and frontal regions. To address this question, we asked participants to remember either color or orientation of one of the two colored gratings for a delay. Using fMRI and an inverted encoding model, we reconstructed population-level, feature-selective responses in the occipital, parietal and frontal cortices during memory maintenance. We found that not only orientation but also color information can be maintained in higher-order parietal and frontal cortices as well as the early visual cortex when it was cued to be remembered. Conversely, neither the task-irrelevant feature of the cued object, nor any feature of the uncued object was maintained in the occipital, parietal, or frontal cortices. These results suggest a highly selective mechanism of visual working memory that maintains task-relevant features only.

Infants' object processing is guided specifically by social cues

Previous studies showed that the movements of another person's eyes and head guides infants' attention and promotes social learning by leading to enhanced encoding of cued objects. However, it is an open question whether social features like eyes are required or if the lateral movement of any arbitrary stimulus can elicit similar effects. The current experiments investigate the effects of the movement of a nonsocial cue and a perceptually similar social cue on object processing in 4-month-olds using event-related potentials (ERPs). Infants were presented with one of two central cues, either a box with a checkerboard pattern or a box with eye-like features on the front, which turned to one side. The cue thereby either turned toward a novel object or turned away from it. Afterwards, the object was presented again and ERPs in response to these previously cued or uncued objects were compared. When the nonsocial box served as the cue, no difference in neural processing of previously cued and uncued objects was found. In contrast, when the box with eyes served as the cue, we found an enhanced positive slow wave (PSW) for uncued as compared to cued objects. While the turning of the box with eyes promoted the encoding of cued objects, uncued objects needed enhanced activity for processing when presented for a second time. Results suggest that not every dynamic cue can influence infants’ object processing but that the presence of a basic social characteristic like isolated schematic eyes is sufficient to enhance social learning processes in early infancy. This hints on a specific sensitivity of the infant brain to social information which helps infants to focus on relevant information in the environment during social learning.

Follow My Gaze: Face Race and Sex Influence Gaze-Cued Attention in Infancy.

Using the eye gaze of others to direct one's own attention develops during the first year of life and is thought to be an important skill for learning and social communication. However, it is currently unclear whether infants differentially attend to and encode objects cued by the eye gaze of individuals within familiar groups (e.g., own race, more familiar sex) relative to unfamiliar groups (e.g., other race, less familiar sex). During gaze cueing, but prior to the presentation of objects, 10-month-olds looked longer to the eyes of own-race faces relative to 5-month-olds and relative to the eyes of other-race faces. After gaze cueing, two objects were presented alongside the face and at both ages, infants looked longer to the uncued objects for faces from the more familiar-sex and longer to cued objects for the less familiar-sex faces. Finally, during the test phase, both 5- and 10-month-old infants looked longer to uncued objects relative to cued objects but only when the objects were cued by an own-race and familiar-sex individual. Results demonstrate that infants use face eye gaze differently when the cue comes from someone within a highly experienced group.

Reduced object-based perception in the near-hand space.

Previous studies have shown that hand proximity changes visual perception (Abrams et al. in Cognition 107(3):1035-1047, 2008). The present study examined the effects of hand proximity on object-based perception. In three experiments, participants viewed stimuli that were either near to or far from their hands. The target stimulus appeared, after a cue, in one of two rectangular objects: either at the location that had been previously cued, at the uncued end of the cued object, or in the uncued object. We found a significantly reduced same-object benefit in reaction time for stimuli near the hands in one experiment. Interestingly, we observed a same-object cost in sensitivity for stimuli near the hands in another experiment. The results reveal that object-based perception is disrupted in the near-hand space. This is consistent with previous findings revealing altered visual processing near the hands.

Voluntary spatial attention induces spatial facilitation and object-centered suppression.

Many daily activities require encoding spatial locations relative to a reference object (e.g., "leftness"), known as object-centered space. Integrating object-centered space and visual attention, this study reports a new form of attention called object-centered suppression, as revealed by a novel object-centered paradigm. Specifically, after cueing a location within an object (e.g., on the left), performance at 2 locations within another, uncued object was worse for the location that shared the same object-centered space as the cued location (e.g., on the left) than the location that did not (e.g., on the right). Because these 2 locations were equidistant to the cued location and because both appeared within the same object, the effect could not be explained by space-based or object-based accounts of attention. Alternative accounts based on attentional capture were also refuted. Instead, a novel object-centered Simon effect (stimulus-response interference) reveals automatic object-centered spatial coding, supporting an object-centered account: when attention is disengaged from an invalidly cued location, a negative attention priority signal at the cued location is tagged and transferred across objects in an object-centered manner. Object-centered suppression therefore unveils a new functional footprint of voluntary spatial attention, integrating space-based and object-based selection through object-centered space.

Rapid forgetting prevented by retrospective attention cues.

Recent studies have demonstrated that memory performance can be enhanced by a cue which indicates the item most likely to be subsequently probed, even when that cue is delivered seconds after a stimulus array is extinguished. Although such retro-cuing has attracted considerable interest, the mechanisms underlying it remain unclear. Here, we tested the hypothesis that retro-cues might protect an item from degradation over time. We employed two techniques that previously have not been deployed in retro-cuing tasks. First, we used a sensitive, continuous scale for reporting the orientation of a memorized item, rather than binary measures (change or no change) typically used in previous studies. Second, to investigate the stability of memory across time, we also systematically varied the duration between the retro-cue and report. Although accuracy of reporting uncued objects rapidly declined over short intervals, retro-cued items were significantly more stable, showing negligible decline in accuracy across time and protection from forgetting. Retro-cuing an object’s color was just as advantageous as spatial retro-cues. These findings demonstrate that during maintenance, even when items are no longer visible, attention resources can be selectively redeployed to protect the accuracy with which a cued item can be recalled over time, but with a corresponding cost in recall for uncued items.

Disentangling the Effects of an Adult Model's Eye Gaze and Head Orientation on Young Infants' Processing of a Previously Attended Object

In order to disentangle the effects of an adult model's eye gaze and head orientation on infants' processing of objects attended to by the adult, we presented 4‐month‐olds with faces that either (1) shifted eye gaze toward or away from an object while the head stayed stationary or (2) that turned their head while maintaining gaze directed straight ahead. Infants' responses to the previously attended and unattended objects were measured using eye‐tracking and event‐related potentials. In both conditions, infants responded to objects that were not cued by the adult's head or eye gaze shift with more visual attention and an increased negative central (Nc) component relative to cued objects. This suggests that cued objects had been encoded more effectively, whereas uncued objects required further processing. We conclude that eye gaze and head orientation act independently as cues to direct infants' attention and object processing. Both head orientation and eye gaze, when presented in motion, even override the effects of incongruent stationary information from the other kind of cue.

Object-based attentional effects in response to eye-gaze and arrow cues

Recent studies have demonstrated that central cues, such as eyes and arrows, reflexively trigger attentional shifts. However, it is not clear whether the attention induced by these two cues can be attached to objects within the visual scene. In the current study, subjects' attention was directed to one of two objects (square outlines) via the observation of uninformative directional arrows or eye gaze. Then, the objects rotated 90° clockwise or counter-clockwise to a new location and the target stimulus was presented within one of these two objects. Results showed that independent of the cue type participants responded faster to targets in the cued object than to those in the uncued object. This suggests that in dynamic displays, both gaze and arrow cues are able to trigger reflexive shifts of attention to objects moving within the visual scene.

Head and eye movements affect object processing in 4‐month‐old infants more than an artificial orientation cue

This study investigates the effects of attention-guiding stimuli on 4-month-old infants' object processing. In the human head condition, infants saw a person turning her head and eye gaze towards or away from objects. When presented with the objects again, infants showed increased attention in terms of longer looking time measured by eye tracking and an increased Nc amplitude measured by event-related potentials (ERP) for the previously uncued objects versus the cued objects. This suggests that the uncued objects were previously processed less effectively and appeared more novel to the infants. In a second condition, a car instead of a human head turned towards or away from objects. Eye-tracking results did not reveal any significant difference in infants' looking time. ERPs indicated only a marginally significant effect in late slow-wave activity associated with memory encoding for the uncued objects. We conclude that human head orientation and gaze direction affect infants' object-directed attention, whereas movement and orientation of a car have only limited influence on infants' object processing.

Vowel perception and production in Turkish children acquiring L2 German

First language (L1) phonological categories strongly influence late learners' perception and production of second language (L2) categories. For learners who start learning an L2 early in life (“early learners”), this L1 influence appears to be substantially reduced or at least more variable. In this paper, we examine the age at which L1 vowel categories influence the acquisition of L2 vowels. We tested a child population with a very narrow range of age of first exposure, controlling for the use of L1 vs. L2, and various naturally produced contrasts that are not allophonic in the L1 of the children. An oddity discrimination task provided evidence that children who are native speakers of Turkish and began learning German as an L2 in kindergarten categorized difficult German contrasts differently from age-matched native speakers. Their vowel productions of these same contrasts (un-cued object naming) were mostly target-like.

Object-based control of attention is sensitive to recent experience.

How is attention guided by past experience? In visual search, numerous studies have shown that recent trials influence responses to the current trial. Repeating features such as color, shape, or location of a target facilitates performance. Here we examine whether recent experience also modulates a more abstract dimension of attentional control, object-based and location-based control. Participants performed a cued target discrimination task with stimuli presented on 2 rectangles. Response times to targets appearing in an uncued location on a cued rectangle were faster than to targets on the uncued rectangle, demonstrating an object-based attentional benefit. We investigated the object-based benefit on the current trial contingent on the cue-target relationship on the previous trial. The object-based benefit was significant only when the cued object contained the target on the previous trial, not when the uncued object contained the target. This effect of recent experience was not due to either the repetition of spatial cue-target location or the repetition of the response, but to adaptation to contingencies in the environment. Our results suggest a unifying view of attentional control that spans the concrete dimensions of control (e.g., determining the relative importance of red vs. blue) to the abstract (determining the relative importance of objects vs. locations in space). Attention closely tracks the short time scale structure of the environment and automatically adapts to optimize performance to this structure.

Eye gaze versus arrows as spatial cues: Two qualitatively different modes of attentional selection.

This study aimed to evaluate the type of attentional selection (location- and/or object-based) triggered by two different types of central noninformative cues: eye gaze and arrows. Two rectangular objects were presented in the visual field, and subjects' attention was directed to the end of a rectangle via the observation of noninformative directional arrows or eye gaze. Similar experiments with peripheral cues have shown an object-based effect: faster target identification when the target is presented on the cued object as compared to the uncued object, even when the distance between target and cue was the same. The three reported experiments aimed to compare the location- and object-based attentional orienting observed with arrows and eye gaze, in order to dissociate the orienting mechanisms underlying the two types of orienting cues. Results showed similar cueing effects on the cued versus oppositely cued locations for the two cue types, replicating several studies with nonpredictive gaze and arrow cues. However, a pure object-based effect occurred only when an arrow cue was presented, whereas a pure location-based effect was only found for eye-gaze cues. It is suggested that attention is nonspecifically directed to nearby objects when a noninformative arrow is used as cue, whereas it is selectively directed to a specific cued location when noninformative eye gaze is used. This may be mediated by theory of mind mechanisms.

On the Relationship between Space- and Object-Based Attention

Visual attention research has suggested two distinct and complementary forms of selection: space- and object-based attention. Though attention can be allocated to regions of space as well as perceptual objects, the exact relationship between the two modes of selection is not fully understood yet. Egly, Driver, and Rafal (1994) first demonstrated spatial- and object-based effects within a single paradigm. However, the space- and object-based reference frames overlapped—targets appeared at the cued location inside the cued object on a large majority of trials. The present study dissociated object and location using a variant of the Egly paradigm. Participants performed a shape discrimination task (T- versus L-shaped stimuli) in which the target appeared at a cued or uncued location inside a cued or uncued object. The cue denoted object, but not spatial, validity. We found both spatial- and object-cueing effects, as well as an interaction between spatial and object validity—the object-based effect occurred at both uncued and cued locations, but was smaller when the spatial location was cued. The results suggest that selection is fundamentally location based, which occurs automatically even under conditions of high object validity.

Shifting attention in viewer- and object-based reference frames after unilateral brain injury

The aims of the present study were to investigate the respective roles that object- and viewer-based reference frames play in reorienting visual attention, and to assess their influence after unilateral brain injury. To do so, we studied 16 right hemisphere injured (RHI) and 13 left hemisphere injured (LHI) patients. We used a cueing design that manipulates the location of cues and targets relative to a display comprised of two rectangles (i.e., objects). Unlike previous studies with patients, we presented all cues at midline rather than in the left or right visual fields. Thus, in the critical conditions in which targets were presented laterally, reorienting of attention was always from a midline cue. Performance was measured for lateralized target detection as a function of viewer-based (contra- and ipsilesional sides) and object-based (requiring reorienting within or between objects) reference frames. As expected, contralesional detection was slower than ipsilesional detection for the patients. More importantly, objects influenced target detection differently in the contralesional and ipsilesional fields. Contralesionally, reorienting to a target within the cued object took longer than reorienting to a target in the same location but in the uncued object. This finding is consistent with object-based neglect. Ipsilesionally, the means were in the opposite direction. Furthermore, no significant difference was found in object-based influences between the patient groups (RHI vs. LHI). These findings are discussed in the context of reference frames used in reorienting attention for target detection.

Hemispheric Asymmetry in the Remapping and Maintenance of Visual Saliency Maps: A TMS Study

Parietal cortex has been implicated in the updating, after eye movements, of a salience map that is required for coherent visual experience and for the control of visually guided behavior. The current experiment investigated whether TMS over anterior intraparietal cortex (AIPCx), just after a saccade, would affect the ability to update and maintain a salience map. In order to generate a salience map, we employed a paradigm in which an uninformative cue was presented at one object in a display to generate inhibition of return (IOR)-an inhibitory tag that renders the cued object less salient than others in the display, and that slows subsequent responses to visual transients at its location. Following the cue, participants made a saccade to either left or right, and we then probed for updating of the location of IOR by measuring manual reaction time to targets appearing at cued location of the cued compared to an uncued object. Between the time of saccade initiation and target appearance, dual-pulse TMS was targeted over right (Experiment 1) or left AIPCx (Experiment 2), and a vertex control side. Updating of the location of IOR was eliminated by TMS over right, but not the left, AIPCx, suggesting that right parietal cortex is involved in the remapping of IOR. Remapping was eliminated by right AIPCx, regardless of whether the saccade was made to the left (contralateral), or right (ipsilateral) visual field, and regardless of which field the target appeared in. We conclude that right AIPCx is the neural substrate for maintaining a salience map across saccades, and not simply for propagating an efference copy of saccade commands.