An age-related view of the role of object and spatial cognitive styles in distance estimation

Distance estimations require identifying characteristics of the object and its spatial surroundings. With the present study, we examined the relationship between visual object and spatial (cognitive) styles and distance estimations in children and adults. Participants were administered the Object-Spatial Imagery Questionnaire (OSIQ) and two distance estimation tasks—one required estimating reach distance (reach task [RT]) from the self and the other required estimating distance between targets (perceptual task[PT]). Overall, our findings indicated that age was the best predictor of estimation for RT and PT tasks, and individuals were more accurate in the task requiring an egocentric frame of reference (RT) compared to tasks that require allocentric judgements (PT). In addition, children had higher ratings on cognitive styles in comparison to adults, but both object and spatial styles only related to RT accuracy in adults. Cognitive styles seem to be associated to distance estimation accuracy, but only when there is a clear preference.     

View-invariant object category learning, recognition, and search: how spatial and object attention are coordinated using surface-based attentional shrouds

How does the brain learn to recognize an object from multiple viewpoints while scanning a scene with eye movements? How does the brain avoid the problem of erroneously classifying parts of different objects together? How are attention and eye movements intelligently coordinated to facilitate object learning? A neural model provides a unified mechanistic explanation of how spatial and object attention work together to search a scene and learn what is in it. The ARTSCAN model predicts how an object's surface representation generates a form-fitting distribution of spatial attention, or "attentional shroud". All surface representations dynamically compete for spatial attention to form a shroud. The winning shroud persists during active scanning of the object. The shroud maintains sustained activity of an emerging view-invariant category representation while multiple view-specific category representations are learned and are linked through associative learning to the view-invariant object category. The shroud also helps to restrict scanning eye movements to salient features on the attended object. Object attention plays a role in controlling and stabilizing the learning of view-specific object categories. Spatial attention hereby coordinates the deployment of object attention during object category learning. Shroud collapse releases a reset signal that inhibits the active view-invariant category in the What cortical processing stream. Then a new shroud, corresponding to a different object, forms in the Where cortical processing stream, and search using attention shifts and eye movements continues to learn new objects throughout a scene. The model mechanistically clarifies basic properties of attention shifts (engage, move, disengage) and inhibition of return. It simulates human reaction time data about object-based spatial attention shifts, and learns with 98.1% accuracy and a compression of 430 on a letter database whose letters vary in size, position, and orientation. The model provides a powerful framework for unifying many data about spatial and object attention, and their interactions during perception, cognition, and action.     

Routes to object constancy: Implications from neurological impairments of object constancy

Previous studies have established the existence of neurological impairments of object constancy: the ability to recognize that an object has the same structure across changes in its retinal projection. Five case studies of brain-damaged patients with deficits in achieving object constancy are reported. To test object constancy, patients discriminated two photographs of a target object, taken from different views, from a photograph of a visually similar distractor object. Four patients showed impaired matching only when the principal axis of the target object in one photograph was foreshortened. The fifth patient showed impaired matching only when the saliency of the target object's primary distinctive feature was reduced. This double dissociation suggests that normally there may be two independent means of achieving object constancy: one by processing an object's local distinctive features, the other by describing the object's structure relative to the frame of its principal axis. Neurological damage can selectively impair either process. Further, this impairment can be independent of deficits in processing visual form, since two patients with a selective deficit in the foreshortened matching task showed relatively normal form discrimination. The patient dependent on local distinctive feature information showed a deficit in size discrimination. It is suggested that this patient fails to utilize global properties of form. This failure may underlie both his impairment in achieving object constancy and in processing certain dimensions of form.     

Localized attentional interference affects object individuation, not feature detection

Modern theorists conceptualize visual selective attention as a competition between object representations for the control of extrastriate receptive fields, an account supported by the finding that attentional selection of one stimulus can degrade processing of nearby stimuli. In the present study the conditions that produce reciprocal interference between attended stimuli are examined. Each display contained either no, one, or two feature-defined target items among an array of homogeneous distractors. Observers performed two tasks, feature detection and object individuation. The feature-detection task required observers to determine if any targets were present within the display. The object-individuation task required observers to determine if the number of targets was exactly two. Spatially mediated interference between target pairs occurred in the object-individuation task, but had no effect on feature detection. Results suggest that localized interference between attended stimuli occurs only when observers are required to resolve the features of individual objects, consistent with the competitive interaction models of attention.     

Spatial distribution of visual attention: Perceptual sensitivity and response latency

Studies of the spatial distribution of visual attention have shown that attentional facilitation monotonically decreases in a graded fashion with increasing distance from an attended location. However, reaction time (RT) measures have typically shown broader gradients than have signal detection (SD) measures of perceptual sensitivity. It is not clear whether these differences have arisen because the stages of information processing indexed by RT measures are different from those indexed by SD measures, or whether these differences are due to methodological confounds in the SD studies. In the present set of experiments, the spatial distribution of attention was studied by using a luminance detection task in an endogenous cuing paradigm that was designed to permit accurate calculations of SD and RT measures for targets at cued and uncued locations. Subjects made target-present/absent decisions at one of six possible cued or uncued upper visual hemifield locations on each trial. The results from three experiments suggest that the differences between broad and focal attentional distributions are not the result of different stages of information processing indexed by RT measures as opposed to SD measures. Rather, the differing distributions appear to reflect variations in attentional allocation strategies induced by the perceptual requirements typical of RT paradigms as opposed to SD paradigms. These findings support numerous prior studies showing that spatial attention affects perceptual sensitivity and that the strategic allocation of attention is a highly flexible process.     

Head up, foot down: object words orient attention to the objects' typical location

Many objects typically occur in particular locations, and object words encode these spatial associations. We tested whether such object words (e.g., head, foot) orient attention toward the location where the denoted object typically occurs (i.e., up, down). Because object words elicit perceptual simulations of the denoted objects (i.e., the representations acquired during actual perception are reactivated), we predicted that an object word would interfere with identification of an unrelated visual target subsequently presented in the object's typical location. Consistent with this prediction, three experiments demonstrated that words denoting objects that typically occur high in the visual field hindered identification of targets appearing at the top of the display, whereas words denoting low objects hindered target identification at the bottom of the display. Thus, object words oriented attention to and activated perceptual simulations in the objects' typical locations. These results shed new light on how language affects perception.     

Grasping possibilities for action: influence of object function and action capabilities

The purpose of this study was to investigate the influence of object function and the observer's action capabilities on grasp facilitation. We used a stimulus-response compatibility (SRC) protocol in which participants were asked to reach and grasp a drinking glass using one of two grasps - the thumb-up or the thumb-down grasp. The reaction time (RT) was used as the index of grasp facilitation. In Experiment 1, we found evidence for the facilitation of "functionally relevant" grasps - where the type of grasp facilitated depended on the location of opening but not the shape of the object. However, this effect was found only when attention was directed toward the location of the opening. In Experiments 2 and 3, we found that this facilitation was also affected by whether participants had the ability to functionally interact with the object. These results show that S-R compatibilities are influenced both by the object's function and the actor's action capabilities, and are interpreted in Gibson's (1979) framework of affordances.     

Seeing and doing: ability to act moderates orientation effects in object perception

We investigated whether the impact of an object's orientation on a perceiver's actions (an orientation effect) is moderated by the perceiver's ability to act on the object in question. To do this, we manipulated the physical location of presented objects (Experiment 1) and the perceiver's action capacity (Experiment 2). Regardless of the physical distance of the object, manual responses were sensitive to the object's orientation (the orientation effect) when the object was within the participant's action range but not when the object was outside of the action range. These results support an embodied view of object perception and shed light on peripersonal space representation.     

Manipulating the disengage operation of covert visual spatial attention

Processes of covert visual spatial attention have been closely linked to the programming of saccadic eye movements. In particular, it has been hypothesized that the reduction in saccadic latency that occurs in the gap paradigm is due to the prior disengagement of covert visual spatial attention. This explanation has received considerable criticism. No study as yet has attempted to demonstrate a facilitation of the disengagement of attention from a covertly attended object. If such facilitation were possible, it would support the hypothesis that the predisengagement of covert attention is necessary for the generation of express saccades. In two experiments using covert orienting of visual attention tasks (COVAT), with a high probability that targets would appear contralateral to the cued location, we attempted to facilitate the disengagement of covert attention by extinguishing peripheral cues prior to the appearance of targets. We hypothesized that the gap between cue offset and target onset would facilitate disengagement of attention from a covertly attended object. For both experiments, responses to targets appearing after a gap were slower than were responses in the no-gap condition. These results suggest that the prior offset of a covertly attended object does not facilitate the disengagement of attention.     

Contextual cueing in multiple object tracking

In this study, we examined whether visual context can be learned through a dynamic display and whether it can facilitate sustained attentional tracking by combining a multiple object tracking (MOT) task and a contextual cueing procedure. The trajectories of the targets and distractors in the MOT task were made invariant by repeatedly presenting them. The results revealed that when the targets were repeatedly displayed, tracking performance implicitly improved, and this effect was enhanced when the unattended distractors in the displays were also repeated. However, the repetition of the distractors alone did not produce any effect. Interestingly, when the targets and distractors were switched in a display in which the distractors had been previously repeated, the tracking performance was impaired as compared with that in the case of nonrepeated displays. We concluded that the contextual information in a dynamic display facilitates attentional tracking and that different types of contextual modulations occurred in MOT processes, such as facilitation for attended targets and inhibition for ignored distractors.     

Object property encoding and change blindness in multiple object tracking

The paradigm of multiple object tracking (MOT) is an established tool for investigating human performance under conditions of divided attention to several objects. We studied change detection ability for colour and shape information in the setting of MOT. Subjects had to detect colour and shape changes during an MOT task. These changes occurred either openly (with nothing to hide them) or with a mud splash in the background to hide the change transient signal. Our experiment demonstrated that (1) when hidden by mud splashes, we fail to perceive a considerable number of colour changes even in the attended objects (i.e., targets) and (2) the visual system is significantly more likely to miss colour and shape changes in distractors than in target. We conclude that a colour change will be detected a lot more efficiently if attention is drawn to its transient. When a simultaneous mud splash hides the transient signal, subjects are significantly less efficient in detecting the change.     

Effects of spatial rearrangement of object components on picture recognition in pigeons.

Five pigeons were first trained to discriminate among line drawings of four objects: a watering can, an iron, a desk lamp, and a sailboat. The birds were then tested with eight versions of each object, in which the object's components were vertically and horizontally rearranged. The pigeons displayed different degrees of generalization decrement to the different scrambled versions of the objects. Two analyses helped to clarify the nature of the varied accuracy scores. First, cluster analyses disclosed subsets of components that were related to test performance. Second, although the clusters varied somewhat across birds for a given object, there was reliable concordance among the subjects in their rankings of the individual scramblings, suggesting that the pigeons may have attended to common aspects of the drawings.     

Selective attention and the perception of an attended nontarget object

Although many theories of attention assume that attending to an object results in the processing of all its feature dimensions, there has been no direct evidence that the irrelevant dimensions of an attended nontarget object are encoded. This article explores factors that modulate such processing. In 6 experiments, participants made a speeded response to a probe preceded by a prime that varied in 2 dimensions. Their reaction times to the probe were influenced by the response compatibility between the relevant and irrelevant dimensions of the prime. Furthermore, the effect was observed only when attention was directed to a nonlocation object feature and when participants' reaction times were relatively long. These results suggest that the effect of attention on a nontarget object is more complex than was previously understood.     

Object and spatial representations in the corner enhancement effect

Cole, Gellatly, and Blurton have shown that targets presented adjacent to geometric corners are detected more efficiently than targets presented adjacent to straight edges. In six experiments, we examined how this corner enhancement effect is modulated by corner-of-object representations (i.e., corners that define an object's shape) and local base-level corners that occur as a result of, for instance, overlapping the straight edges of two objects. The results show that the corner phenomenon is greater for corners of object representations than for corners that do not define an object's shape. We also examined whether the corner effect persists within the contour boundaries of an object, as well as on the outside. The results showed that a spatial gradient of attention accompanies the corner effect outside the contour boundaries of an object but that processing within an object is uniform, with no corner effect occurring. We discuss these findings in relation to space-based and object-based theories of attention.     

Attending to the parts of a single object: part-based selection limitations

Studies of object-based attention have demonstrated poorer performance in dividing attention between two objects in a scene than in focusing attention on a single object. However, objects often are composed of several parts, and parts are central to theories of object recognition. Are parts also important for visual attention? That is, can attention be limited in the number of parts processed simultaneously? We addressed this question in four experiments. In Experiments 1 and 2, participants reported two attributes that appeared on the same part or on different parts of a single multipart object. Participants were more accurate in reporting the attributes on the same part than attributes on different parts. This part-based effect was not influenced by the spatial distance between the parts, ruling out a simple spatial attention interpretation of our results. A control study demonstrated that our spatial manipulation was sufficient to observe shifts of spatial attention. This study revealed an effect of spatial distance, indicating that our spatial manipulation was adequate for observing spatial attention. The absence of a distance effect in Experiments 1 and 2 suggests that part-based attention may not rely entirely on simple shifts of spatial attention. Finally, in Experiment 4 we found evidence for part-based attention, using stimuli controlled for the distance between the parts of an object. The results of these experiments indicate that visual attention can selectively process the parts of an object. We discuss the relationship between parts and objects and the locus of part-based attentional selection.     

Space, object, and task selection

Within the field of selective attention, two separate literatures have developed, one examining the effect of selection of objects and another examining the effect of selection of features. The present study bridged these two traditions by examining the compatibility effects generated by two features of attended and unattended nontarget (foil) stimuli. On each trial, participants determined either the identity or the orientation of a visual stimulus. Spatial attention was controlled using cues (presented prior to the target frame) designed to involuntarily capture attention. We independently manipulated the stimulus dimension the participants prepared for and the stimulus dimension on which they actually executed the task. Preparation had little influence on the magnitude of compatibility effects from foil stimuli. For attended stimuli, the stimulus dimension used in executing the task produced large compatibility effects, regardless of whether that dimension was prepared. These and other compatibility effects (e.g., Stroop effects) are discussed in relation to an integrative model of attentional selection. The key assumptions are that (1) selection occurs at three distinct levels (space, object, and task), (2) spatial attention leads to semantic processing of all dimensions, and (3) features do not automatically activate responses unless that object is selected for action.     

Attending to illusory differences in object size

Focused visual attention can be shifted between objects and locations (attentional orienting) or expanded and contracted in spatial extent (attentional focusing). Although orienting and focusing both modulate visual processing, they have been shown to be distinct, independent modes of attentional control. Objects play a central role in visual attention, and it is known that high-level object representations guide attentional orienting. It not known, however, whether attentional focusing is driven by low-level object representations (which code object size in terms of retinotopic extent) or by high-level representations (which code perceived size). We manipulated the perceived size of physically identical objects by using line drawings or photographs that induced the Ponzo illusion, in a task requiring the detection of a target within these objects. The distribution of attention was determined by the perceived size and not by the retinotopic size of an attended object, indicating that attentional focusing is guided by high-level object representations.     

Effect of object onset on the distribution of visual attention.

There now exists considerable evidence to suggest that the appearance of a new object in the visual field captures visual attention. One of the consequences of this attentional capture is that the object initiates a redistribution of attentional resources across visual space. This is classically observed in the precuing paradigm in which the onset of an abrupt cue influences the processing of a subsequently presented target. The present research describes a new phenomenon that occurs as a result of a new object appearing in the visual field. A stimulus presented in a region of space adjacent to a corner of an onsetting object receives an enhancement of processing relative to a stimulus presented adjacent to one of the object's straight edges. With the use of 2 converging methods, evidence is presented that suggests that the effect is a higher order attentional phenomenon whereby greater resources become directed to the corners of objects.     

Differential use of distance and location information for spatial localization

Five experiments are reported in which subjects judged the movement or spatial location of a visible object that underwent a combination of real and induced (illusory) motion. When subjects attempted to reproduce the distance that the object moved by moving their unseen hands, they were more affected by the illusion than when they pointed to the object's perceived final location. Furthermore, pointing to the final location was more affected by the illusion when the hand movement began from the same position as that at which the object initially appeared, as compared with responses that began from other positions. The results suggest that people may separately encode two distinct types of spatial information: (1) information about the distance moved by an object and (2) information about the absolute spatial location of the object. Information about distance is more susceptible to the influence of an induced motion illusion, and people appear to rely differentially on the different types of spatial information, depending on features of the pointing response. The results have important implications for the mechanisms that underlie spatially oriented behavior in general.