The role of visual and semantic codes in object naming

Three experiments investigated the effects of familiarity, practice, and stimulus variability on naming latencies for photographs of objects. Latencies for pictures of objects having the same name decreased most with practice when the same picture was always used to represent a given object (Condition Ps-Ns), less if different views of the same object were used (Condition Pv-Ns), and least if pictures of different objects having the same name were used (Condition Pd-Ns). In all cases, however, the effect of practice was significant. The savings in naming latency associated with practice on Conditions Ps-Ns and Pv-Ns showed almost no transfer to condition Pd-Ns, even though the same responses were being given before and after transfer. However, practice on Condition Ps-Ns transferred completely to Condition Pv-Ns. Name frequency affected latency in all conditions. The frequency effect decreased slightly with practice.These results are related to several alternative models of the coding processes involved in naming objects. It is concluded that at least three types of representation may be necessary: visual codes, nonverbal semantic codes, and name codes. A distinction is made between visual codes that characterize two-dimensional stimuli and those that characterize three-dimensional objects.     

Quantifying the role of context in visual object recognition

An object's context may serve as a source of information for recognition when the object's image is degraded. The current study aimed to quantify this source of information. Stimuli were photographs of objects divided into quantized blocks. Participants decreased block size (increasing resolution) until identification. Critical resolution was compared across three conditions: (1) when the picture of the target object was shown in isolation, (2) in the object's contextual setting where that context was unfamiliar to the participant, and (3) where that context was familiar to the participant. A second experiment assessed the role of object familiarity without context. Results showed a profound effect of context: Participants identified objects in familiar contexts with minimal resolution. Unfamiliar contexts required higher-resolution images, but much less so than those without context. Experiment 2 found a much smaller effect of familiarity without context, suggesting that recognition in familiar contexts is primarily based on object-location memory.     

The role of surface-based representations of shape in visual object recognition

This study contrasted the role of surfaces and volumetric shape primitives in three-dimensional object recognition. Observers (N?=?50) matched subsets of closed contour fragments, surfaces, or volumetric parts to whole novel objects during a whole–part matching task. Three factors were further manipulated: part viewpoint (either same or different between component parts and whole objects), surface occlusion (comparison parts contained either visible surfaces only, or a surface that was fully or partially occluded in the whole object), and target–distractor similarity. Similarity was varied in terms of systematic variation in nonaccidental (NAP) or metric (MP) properties of individual parts. Analysis of sensitivity (d′) showed a whole–part matching advantage for surface-based parts and volumes over closed contour fragments—but no benefit for volumetric parts over surfaces. We also found a performance cost in matching volumetric parts to wholes when the volumes showed surfaces that were occluded in the whole object. The same pattern was found for both same and different viewpoints, and regardless of target–distractor similarity. These findings challenge models in which recognition is mediated by volumetric part-based shape representations. Instead, we argue that the results are consistent with a surface-based model of high-level shape representation for recognition.     

Multidimensional shape similarity in the development of visual object classification

The current work examined age differences in the classification of novel object images that vary in continuous dimensions of structural shape. The structural dimensions employed are two that share a privileged status in the visual analysis and representation of objects: the shape of discrete prominent parts and the attachment positions of those parts. Experiment 1 involved a triad classification task in which participants at each of three different ages (5 years, 8 years, and adult) classified object images from two distinct stimulus sets. Across both sets, the youngest children demonstrated a systematic bias toward the shape of discrete parts during their judgments. With increasing age, participants increasingly came to select both the shape and the position of parts when classifying the images. The findings from Experiment 2 indicate that the local shape bias observed in young children's classifications is not merely a consequence of a discrimination advantage for that dimension. Results are discussed in relation to corresponding age-related changes in other functional contexts of visual processing.     

The role of the object in drive cathexis and psychosexual development.

Alternate axes are explored in the orthodox formulation of drive cathexis and psychosexual development, with implications for corresponding object relation modes engendered by these processes. Somatic and defensive aspects are shown to impact on the function of the "other" as the individual matures. The separation/individuation process is subsumed into this overall developmental continuum, and the centrality of the object as a focus in cathexis and drive delineation is critically evaluated. The homeostatic notion of equilibration is appealed to in synthesizing the factors emerging from the analysis.     

A role for action knowledge in visual object identification

We evaluated the impact of visual similarity and action similarity on visual object identification. We taught participants to associate novel objects with nonword labels and verified that in memory visually similar objects were confused more often than visually dissimilar objects. We then taught participants to associate novel actions with nonword labels and verified that similar actions were confused moreoften th an dissimilaractions. We then paired specific objects with specific actions. Visually similar objects paired with similar actions were confused more often in memory than when these same objects were paired with dissimilar actions. Hence the actions associated with objects served to increase or decrease their separation in memory space, and influenced the ease with which these objects could be identified. These experiments ultimately demonstrated that when identifying stationary objects, the memory of how these object were used dramatically influenced the ability to identify these objects.     

The role of visual attention in multiple object tracking: Evidence from ERPs

We examined the role of visual attention in the multiple object tracking (MOT) task by measuring the amplitude of the N1 component of the event-related potential to probe flashes presented on targets, distractors, or empty background areas. We found evidence that visual attention enhances targets and suppresses distractors (Experiments 1 and 3). However, we also found that when tracking load was light (two targets and two distractors), accurate tracking could be carried out without any apparent contribution from the visual attention system (Experiment 2). Our results suggest that attentional selection during MOT is flexibly determined by task demands, as well as tracking load, and that visual attention may not always be necessary for accurate tracking.     

The role of sensory-motor information in object recognition: evidence from category-specific visual agnosia

The role of sensory-motor representations in object recognition was investigated in experiments involving AD, a patient with mild visual agnosia who was impaired in the recognition of visually presented living as compared to non-living entities. AD named visually presented items for which sensory-motor information was available significantly more reliably than items for which such information was not available; this was true when all items were non-living. Naming of objects from their associated sound was normal. These data suggest that both information about object form computed in the ventral visual system as well as sensory-motor information specifying the manner of manipulation contribute to object recognition.     

The role of local and distal landmarks in the development of object location memory

To locate objects in the environment, animals and humans use visual and nonvisual information. We were interested in children's ability to relocate an object on the basis of self-motion and local and distal color cues for orientation. Five- to 9-year-old children were tested on an object location memory task in which, between presentation and test, the availability of local and distal cues was manipulated. Additionally, participants' viewpoint could be changed. We used a Bayesian model selection approach to compare our hypotheses. We found that, to remain oriented in space, 5-year-olds benefit from visual information in general, 7-year-olds benefit from visual cues when a viewpoint change takes place, and 9-year-olds do not benefit from the availability of visual cues for orientation but rely on self-movement cues instead. Results are discussed in terms of the adaptive combination model (Newcombe & Huttenlocher, 2006).     

Infant development of configural object processing in visual and visual-haptic contexts

Infants’ visual processing of objects is characterised by a developmental trend from a predominantly analytical to a configural processing mode. In two studies with 6- and 8-month-old infants, we sought to replicate this finding in a purely visual condition (inspecting objects), and to examine how far redundant visual-haptic information present in a visual-haptic condition influences the processing mode. Infants were familiarized with two objects differing in three dimensions (texture, size and shape). At test, infants were presented with a familiar object, a switch object consisting of a recombination of familiar dimensions, and a novel object, and looking times were measured. Results indicate a transition from analytical processing at 6 months to configural processing at 8 months in the visual condition. In the visual-haptic condition, both age-groups displayed configural processing. Thus, redundant visual-haptic information seems to enhance object processing.     

A novel paradigm reveals the role of reentrant visual processes in object substitution masking

Object substitution masking (OSM) occurs when an initial display of a target and mask continues with the mask alone, creating a mismatch between the reentrant hypothesis, triggered by the initial display, and the ongoing low-level activity. We tested the proposition that the critical factor in OSM is not whether the mask remains in view after target offset, but whether the representation of the mask is sufficiently stronger than that of the target when the reentrant signal arrives. In Experiment 1, a variable interstimulus interval (ISI) was inserted between the initial display and the mask alone. The trailing mask was presumed to selectively boost the strength of the mask representation relative to that of the target. As predicted, OSM occurred at intermediate ISIs, at which the mask was presented before the arrival of the reentrant signal, creating a mismatch, but not at long ISIs, at which a comparison between the reentrant signal and the low-level activity had already been made. Experiment 2, conducted in dark-adapted viewing, ruled out the possibility that low-level inhibitory contour interactions (metacontrast masking) had played a significant role in Experiment 1. Metacontrast masking was further ruled out in Experiment 3, in which the masking contours were reduced to four small dots. We concluded that OSM does not depend on extended presentation of the mask alone, but on a mismatch between the reentrant signals and the ongoing activity at the lower level. The present results place constraints on estimates of the timing of reentrant signals involved in OSM.     

The role of object recognition in young infants' object segregation

Needham's (2001, this issue) new results confirm that young infants draw on experientially derived representations in resolving individuation ambiguities due to shared boundaries between adjacent objects. They extend previous findings in a surprising way: The memory representations that infants draw upon have bound together information about shape, color, and pattern. Our commentary on these important results draws a distinction between two senses of "recognition" and asks in which sense object recognition contributes to object individuation in these experiments.     

The temporal dynamics of visual object priming

Priming reflects an important means of learning that is mediated by implicit memory. Importantly, priming occurs for previously viewed objects (item-specific priming) and their category relatives (category-wide priming). Two distinct neural mechanisms are known to mediate priming, including the sharpening of a neural object representation and the retrieval of stimulus–response mappings. Here, we investigated whether the relationship between these neural mechanisms could help explain why item-specific priming generates faster responses than category-wide priming. Participants studied pictures of everyday objects, and then performed a difficult picture identification task while we recorded event-related potentials (ERP). The identification task gradually revealed random line segments of previously viewed items (Studied), category exemplars of previously viewed items (Exemplar), and items that were not previously viewed (Unstudied). Studied items were identified sooner than Unstudied items, showing evidence of item-specific priming, and importantly Exemplar items were also identified sooner than Unstudied items, showing evidence of category-wide priming. Early activity showed sustained neural suppression of parietal activity for both types of priming. However, these neural suppression effects may have stemmed from distinct processes because while category-wide neural suppression was correlated with priming behavior, item-specific neural suppression was not. Late activity, examined with response-locked ERPs, showed additional processes related to item-specific priming including neural suppression in occipital areas and parietal activity that was correlated with behavior. Together, we conclude that item-specific and category-wide priming are mediated by separate, parallel neural mechanisms in the context of the current paradigm. Temporal differences in behavior are determined by the timecourses of these distinct processes.     

The accuracy of aimed movements to visual targets during development: the role of visual information

Children aged 1.5 to 8 years were required to touch accurately an illuminated target lamp located on a vertical board. Movements were made when visual information was complete (target lit for 3 s, room illuminated; partial (target lit for 3 s, room dark, and reduced (target lit for 0.7 s, room dark). Dependent variables were response accuracy, reaction time, and movement time. Accuracy decreased with decreasing availability of visual information and improved with age under all conditions. Reaction times were shorter in the dark (Conditions 2 and 3) than in the light; they decreased with age up to age 5 and did not continue to decrease thereafter. Movement time did not change with age under Conditions 1 and 3 but tended to increase with age under Condition 2. Slower movements were more accurate at all ages, provided visual feedback could be utilized. Increased reliance on the strategy "slower movements yield higher accuracy" was held to account for developmental changes under Condition 2, whereas in Conditions 1 and 3 improvement in the efficiency of motor preprogramming was implicated.     

物体表征强度对基于动态物体的注意的影响

基于物体的注意已得到许多静态物体实验的证实, 然而, 对注意分配如何受动态物体影响的研究较少, 存在提示物体假设和动态更新假设两种观点。提示物体假设认为基于物体的注意由最初的物体决定, 而动态更新假设则认为由变化之后的物体决定。动态物体的注意研究还发现了即时物体效应, 即注意基于新物体进行。对于物体变化时注意究竟基于旧物体还是新物体, 新旧物体的相对物体表征强度在其中起决定作用; 当提示物体表征较强时表现为提示物体(即旧物体)决定注意分配, 而当即时物体表征较强时表现为即时物体(即新物体)决定注意分配。相对物体表征强度的概念对理解物体动态变化情况下基于物体的注意的分配以及解决相关理论之冲突可能有重要作用。     

The influence of location and visual features on visual object memory

In five experiments, we examined the influence of contextual objects’ location and visual features on visual memory. Participants’ visual memory was tested with a change detection task in which they had to judge whether the orientation (Experiments 1A, 1B, and 2) or color (Experiments 3A and 3B) of a target object was the same. Furthermore, contextual objects’ locations and visual features were manipulated in the test image. The results showed that change detection performance was better when contextual objects’ locations remained the same from study to test, demonstrating that the original spatial configuration is important for subsequent visual memory retrieval. The results further showed that changes to contextual objects’ orientation, but not color, reduced orientation change detection performance; and changes to contextual objects’ color, but not orientation, impaired color change detection performance. Therefore, contextual objects’ visual features are capable of affecting visual memory. However, selective attention plays an influential role in modulating such effects.     

The role of context in object recognition

In the real world, objects never occur in isolation; they co-vary with other objects and particular environments, providing a rich source of contextual associations to be exploited by the visual system. A natural way of representing the context of an object is in terms of its relationship to other objects. Alternately, recent work has shown that a statistical summary of the scene provides a complementary and effective source of information for contextual inference, which enables humans to quickly guide their attention and eyes to regions of interest in natural scenes. A better understanding of how humans build such scene representations, and of the mechanisms of contextual analysis, will lead to a new generation of computer vision systems.