Learned prediction affects body perception

Learning to recognize objects appears to depend critically on extended observation of appearance over time. Specifically, temporal association between dissimilar views of an object has been proposed as a tool for learning invariant representations for recognition. We examined heretofore untested aspects of the temporal association hypothesis using a familiar dynamic object, the human body. Specifically, we examined the role of appearance prediction (temporal asymmetry) in temporal association. In our task, observers performed a change detection task using upright and inverted images of a walking body either with or without previous exposure to a motion stimulus depicting an upright walker. Observers who were exposed to the dynamic stimulus were further divided into two groups dependent on whether the observed motion depicted forward or backward walking. We find that the effect of the motion stimulus on sensitivity is highly dependent on whether the observed motion is consistent with past experience.     

Encoding 'regular' and 'random' sequences of views of novel three-dimensional objects

When we look at an object as we move or the object moves, our visual system is presented with a sequence of different views of the object. It has been suggested that such regular temporal sequences of views of objects contain information that can aid in the process of representing and recognising objects. We examined whether seeing a series of perspective views of objects in sequence led to more efficient recognition than seeing the same views of objects but presented in a random order. Participants studied images of 20 novel three-dimensional objects rotating in depth under one of two study conditions. In one study condition, participants viewed an ordered sequence of views of objects that was assumed to mimic important aspects of how we normally encounter objects. In the other study condition, participants were presented the same object views, but in a random order. It was expected that studying a regular sequence of views would lead to more efficient recognition than studying a random presentation of object views. Although subsequent recognition accuracy was equal for the two groups, differences in reaction time between the two study groups resulted. Specifically, the random study group responded reliably faster than the sequence study group. Some possible encoding differences between the two groups are discussed.     

Visual object detection, categorization, and identification tasks are associated with different time courses and sensitivities

Recent evidence suggests that the recognition of an object's presence and its explicit recognition are temporally closely related. Here we re-examined the time course (using a fine and a coarse temporal resolution) and the sensitivity of three possible component processes of visual object recognition. In particular, participants saw briefly presented (Experiment I to III) or noise masked (Experiment IV) static images of objects and non-object textures. Participants reported the presence of an object, its basic level category, and its subordinate category while we measured recognition performance by means of accuracy and reaction times. All three recognition tasks were clearly separable in terms of their time course and sensitivity. Finally, the use of a coarser temporal sampling of presentation times decreased performance differences between the detection and basic level categorization task suggesting that a fine temporal sampling for the dissociation of recognition performances is important. Overall the three probed recognition processes were associated with different time courses and sensitivities.     

Temporal properties of disparity processing revealed by dynamic random-dot stereograms

In studies of the temporal flexibility of the stereoscopic system, it has been suggested that two different processes of binocular depth perception could be responsible for the flexibility: tolerance for interocular delays and temporal integration of correlation. None has investigated the relationship between tolerance for delays and temporal integration mechanisms and none has revealed which mechanism is responsible for depth perception in dynamic random-dot stereograms. We address these questions in the present study. Across five experiments, we investigated the temporal properties of stereopsis by varying interocular correlation as a function of time in controlled ways. We presented different types of dynamic random-dot stereograms, each consisting of two pairs of alternating random-dot patterns. Our experimental results demonstrate that (i) disparities from simultaneous monocular inputs dominate those from interocular delayed inputs; (ii) stereopsis is limited by temporal properties of monocular luminance mechanisms; and (iii) depth perception in dynamic random-dot stereograms results from cross-correlation-like operation on two simultaneous monocular inputs that represent the retinal images after having been subjected to a process of monocular temporal integration of luminance.     

Transcranial magnetic stimulation over MT/MST fails to impair judgments of implied motion

The medial temporal and medial superior temporal cortex (MT/MST) is involved in the processing of visual motion, and fMRI experiments indicate that there is greater activation when subjects view static images that imply motion than when they view images that do not imply motion at all. We applied transcranial magnetic stimulation (TMS) to MT/MST in order to assess the functional necessity of this region for the processing of implied motion represented in static images. Area MT/MST was localized by the use of a TMS-induced misperception of visual motion, and its location was verified through the monitored completion of a motion discrimination task. We controlled for possible impairments in general visual processing by having subjects perform an object categorization task with and without TMS. Although MT/MST stimulation impaired performance in a motion discrimination task (and vertex stimulation did not), there was no difference in performance between the two forms of stimulation in the implied motion discrimination task. MT/MST stimulation did, however, improve subjects’ performance in the object categorization task. These results indicate that, within 150 msec of stimulus presentation, MT/MST is not directly involved in the visual processing of static images in which motion is implied. The results do, however, confirm previous findings that disruption of MT/MST may improve efficiency in more ventral visual processing streams.     

Wistar rats show episodic-like memory for unique experiences

Human episodic memory refers to the recollection of an unique past experience in terms of its details, its locale, and temporal occurrence. Episodic memory, even in principle, has been difficult to demonstrate in non-verbal mammals. Previously, we provided evidence that mice are able to form an integrated memory for "what," "where," and "when" aspects of single experiences by combining different versions of the novelty-preference paradigm, i.e., object recognition memory, the memory for locations in which objects were explored, and the temporal order memory for objects presented at distinct time points. In the present series of experiments we evaluated whether this paradigm, with minor modifications, also works with rats. We found that rats spent more time exploring an "old familiar" object relative to a "recent familiar" object, suggesting that they recognized objects previously explored during separate trials and remembered their order of presentation. Concurrently, the rats responded differentially to spatial object displacement dependent on whether an "old familiar" or "recent familiar" object was shifted to a location, where it was not encountered previously. These results provide strong evidence that the rats established an integrated memory for "what," "where," and "when." We also found that acute stress impaired the animal's performance in the episodic-like memory task, which, however, could be partially reversed by the N-Methyl-D-aspartate-receptors agonist D-cycloserine.     

Speech segmentation is facilitated by visual cues

Evidence from infant studies indicates that language learning can be facilitated by multimodal cues. We extended this observation to adult language learning by studying the effects of simultaneous visual cues (nonassociated object images) on speech segmentation performance. Our results indicate that segmentation of new words from a continuous speech stream is facilitated by simultaneous visual input that it is presented at or near syllables that exhibit the low transitional probability indicative of word boundaries. This indicates that temporal audio-visual contiguity helps in directing attention to word boundaries at the earliest stages of language learning. Off-boundary or arrhythmic picture sequences did not affect segmentation performance, suggesting that the language learning system can effectively disregard noninformative visual information. Detection of temporal contiguity between multimodal stimuli may be useful in both infants and second-language learners not only for facilitating speech segmentation, but also for detecting word–object relationships in natural environments.     

Distinct mechanisms for the representation of moving and static objects

The visual system has been suggested to integrate different views of an object in motion. We investigated differences in the way moving and static objects are represented by testing for priming effects to previously seen ("known") and novel object views. We showed priming effects for moving objects across image changes (e.g., mirror reversals, changes in size, and changes in polarity) but not over temporal delays. The opposite pattern of results was observed for objects presented statically; that is, static objects were primed over temporal delays but not across image changes. These results suggest that representations for moving objects are: (1) updated continuously across image changes, whereas static object representations generalize only across similar images, and (2) more short-lived than static object representations. These results suggest two distinct representational mechanisms: a static object mechanism rather spatially refined and permanent, possibly suited for visual recognition, and a motion-based object mechanism more temporary and less spatially refined, possibly suited for visual guidance of motor actions.     

Action enhances auditory but not visual temporal sensitivity

People naturally dance to music, and research has shown that rhythmic auditory stimuli facilitate production of precisely timed body movements. If motor mechanisms are closely linked to auditory temporal processing, just as auditory temporal processing facilitates movement production, producing action might reciprocally enhance auditory temporal sensitivity. We tested this novel hypothesis with a standard temporal-bisection paradigm, in which the slope of the temporal-bisection function provides a measure of temporal sensitivity. The bisection slope for auditory time perception was steeper when participants initiated each auditory stimulus sequence via a keypress than when they passively heard each sequence, demonstrating that initiating action enhances auditory temporal sensitivity. This enhancement is specific to the auditory modality, because voluntarily initiating each sequence did not enhance visual temporal sensitivity. A control experiment ruled out the possibility that tactile sensation associated with a keypress increased auditory temporal sensitivity. Taken together, these results demonstrate a unique reciprocal relationship between auditory time perception and motor mechanisms. As auditory perception facilitates precisely timed movements, generating action enhances auditory temporal sensitivity.     

The role of sequence order in determining view canonicality for novel wire-frame objects

Objects are best recognized from so-called “canonical” views. The characteristics of canonical views of arbitrary objects have been qualitatively described using a variety of different criteria, but little is known regarding how these views might be acquired during object learning. We address this issue, in part, by examining the role of object motion in the selection of preferred views of novel objects. Specifically, we adopt a modeling approach to investigate whether or not the sequence of views seen during initial exposure to an object contributes to observers’ preferences for particular images in the sequence. In two experiments, we exposed observers to short sequences depicting rigidly rotating novel objects and subsequently collected subjective ratings of view canonicality (Experiment 1) and recall rates for individual views (Experiment 2). Given these two operational definitions of view canonicality, we attempted to fit both sets of behavioral data with a computational model incorporating 3-D shape information (object foreshortening), as well as information relevant to the temporal order of views presented during training (the rate of change for object foreshortening). Both sets of ratings were reasonably well predicted using only 3-D shape; the inclusion of terms that capture sequence order improved model performance significantly.     

A computational and neuropsychological account of object-oriented behaviours in infancy

Infants under 7 months of age fail to reach behind an occluding screen to retrieve a desired toy even though they possess sufficient motor skills to do so. However, even by 3.5 months of age they show surprise if the solidity of the hidden toy is violated, suggesting that they know that the hidden toy still exists. We describe a connectionist model that learns to predict the position of objects and to initiate a response towards these objects. The model embodies the dual-route principle of object information processing characteristic of the cortex. One route develops a spatially invariant surface feature representation of the object whereas the other route develops a feature blind spatial–temporal representation of the object. The model provides an account of the developmental lag between infants’ knowledge of hidden objects and their ability to demonstrate that knowledge in an active retrieval task, in terms of the need to integrate information across multiple object representations using (associative) connectionist learning algorithms. Finally, the model predicts the presence of an early dissociation between infants’ ability to use surface features (e.g. colour) and spatial–temporal features (e.g. position) when reasoning about hidden objects. Evidence supporting this prediction has now been reported.     

Do infants recognize the Arcimboldo images as faces? Behavioral and near-infrared spectroscopic study

Arcimboldo images induce the perception of faces when shown upright despite the fact that only nonfacial objects such as vegetables and fruits are painted. In the current study, we examined whether infants recognize a face in the Arcimboldo images by using the preferential looking technique and near-infrared spectroscopy (NIRS). In the first experiment, we measured looking preference between upright and inverted Arcimboldo images among 5- and 6-month-olds and 7- and 8-month-olds. We hypothesized that if infants perceive the Arcimboldo images as faces, they would prefer the upright images to the inverted ones. We found that only 7- and 8-month-olds significantly preferred upright images, suggesting that they could perceive the Arcimboldo images as faces. In the second experiment, we measured hemodynamic responses using NIRS. Based on the behavioral data, we hypothesized that 7- and 8-month-olds would show different neural activity for upright and inverted Arcimboldo images, as do adults. Therefore, we measured hemodynamic responses in 7- and 8-month-olds while they were looking at upright and inverted Arcimboldo images. Their responses were then compared with the baseline activation during the presentation of individual vegetables. We found that the concentration of oxyhemoglobin increased in the left temporal area during the presentation of the upright images compared with the baseline during the presentation of vegetables. The results of the two experiments suggest that (a) the ability to recognize the upright Arcimboldo images as faces develops at around 7 or 8 months of age and (b) processing of the upright Arcimboldo images is related to the left temporal area of the brain.     

Evolutionary Constraints on Human Object Perception

Language and culture endow humans with access to conceptual information that far exceeds any which could be accessed by a non‐human animal. Yet, it is possible that, even without language or specific experiences, non‐human animals represent and infer some aspects of similarity relations between objects in the same way as humans. Here, we show that monkeys’ discrimination sensitivity when identifying images of animals is predicted by established measures of semantic similarity derived from human conceptual judgments. We used metrics from computer vision and computational neuroscience to show that monkeys’ and humans’ performance cannot be explained by low‐level visual similarity alone. The results demonstrate that at least some of the underlying structure of object representations in humans is shared with non‐human primates, at an abstract level that extends beyond low‐level visual similarity. Because the monkeys had no experience with the objects we tested, the results suggest that monkeys and humans share a primitive representation of object similarity that is independent of formal knowledge and cultural experience, and likely derived from common evolutionary constraints on object representation.     

Every moment counts: smooth transitions of object boundaries reflect constant updating in object-based attention

Detection of a target is faster when it is presented on an attended rather than an unattended object (i.e., object-based attention). Using the double-rectangle cuing paradigm (Egly, Driver, & Rafal, 1994), we previously showed that object-based attention operates on a dynamic representation: Object-based attentional guidance is affected by subsequent changes occurring to an attended object (Lin & Yeh, 2011). The present study provides further support for our dynamic-updating hypothesis, demonstrating that changes are indeed updated into the existing object representation. After a cue display, we introduced changes between the initial display (four hashes) and the final display (four squares with an occluder between them). We found object-based attention only with smooth transitions between the initial and final displays, not when transitions were in the reverse order (Exp. 1) or contained any single disruption of the smooth transition (Exp. 2). These results confirm our hypothesis that attention operates on a dynamic object representation that is constantly and continuously updated.     

Picture recognition of food by macaques (<Emphasis Type="Italic">Macaca silenus</Emphasis>)

Pictorial representations of three-dimensional objects are often used to investigate animal cognitive abilities; however, investigators rarely evaluate whether the animals conceptualize the two-dimensional image as the object it is intended to represent. We tested for picture recognition in lion-tailed macaques by presenting five monkeys with digitized images of familiar foods on a touch screen. Monkeys viewed images of two different foods and learned that they would receive a piece of the one they touched first. After demonstrating that they would reliably select images of their preferred foods on one set of foods, animals were transferred to images of a second set of familiar foods. We assumed that if the monkeys recognized the images, they would spontaneously select images of their preferred foods on the second set of foods. Three monkeys selected images of their preferred foods significantly more often than chance on their first transfer session. In an additional test of the monkeys’ picture recognition abilities, animals were presented with pairs of food images containing a medium-preference food paired with either a high-preference food or a low-preference food. The same three monkeys selected the medium-preference foods significantly more often when they were paired with low-preference foods and significantly less often when those same foods were paired with high-preference foods. Our novel design provided convincing evidence that macaques recognized the content of two-dimensional images on a touch screen. Results also suggested that the animals understood the connection between the two-dimensional images and the three-dimensional objects they represented.     

Lateralized spatial and object memory encoding in entorhinal and perirhinal cortices

The perirhinal and entorhinal cortices are critical components of the medial temporal lobe (MTL) declarative memory system. Study of their specific functions using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI), however, has suffered from severe magnetic susceptibility signal dropout resulting in poor temporal signal-to-noise (tSNR) and thus weak BOLD signal detectability. We have demonstrated that higher spatial resolution in the z-plane leads to improved BOLD fMRI signal quality in the anterior medial temporal lobes when using a 16-element surface coil array at 3 T (Tesla). Using this technique, the present study investigated the roles of the anterior medial temporal lobe, particularly the entorhinal and perirhinal cortices, in both object and spatial memory. Participants viewed a series of fractal images and were instructed to encode either the object's identity or location. Object and spatial recognition memory were tested after 18-sec delays. Both the perirhinal and entorhinal cortices were active during the object and spatial encoding tasks. In both regions, object encoding was biased to the left hemisphere, whereas spatial encoding was biased to the right. A similar hemispheric bias was evident for recognition memory. Recent animal studies suggest functional dissociations among regions of the entorhinal cortex for spatial vs. object processing. Our findings suggest that this process-specific distinction may be expressed in the human brain as a hemispheric division of labor.     

Seeing an image of the hand affects performance on a crossmodal congruency task for sequences of events

The crossmodal congruency effect (CCE) is augmented when viewing an image of a hand compared to an object. It is unclear if this contextual effect extends to a non-spatial CCE. Here, participants discriminated the number of tactile vibrations delivered to the hand whilst ignoring visual distractors on images of their own or another’s hand or an object. The CCE was not modulated by stimulus context. Viewing one’s hand from a third person perspective increased errors relative to viewing an object (Experiment 1). Errors were reduced when viewing hands, from first or third person perspectives, with additional identity markers (Experiments 2 and 3). Our results suggest no effect of context on the non-spatial CCE and that differences in task performance between hand and object images depend on their visual properties. These findings are discussed in light of the relationship between body representation and perception of body-centred stimuli in the temporal domain.     

Failure to Replicate the Increased Temporal Resolution Induced by Images That Give Impression of Danger

Kobayashi and Ichikawa (2016) recently reported that briefly presented images with dangerous impressions were detected with higher accuracy than images with safe impressions and concluded that the emotion evoked by such images improves temporal resolution of visual perception. In this study, we assessed confounding effects of the color saturations of the images used in their study. While attempting to replicate their results, we found the opposite results—that is, images with safe impressions were detected with higher accuracy than those with dangerous impressions. This likely reflected an observed correlation between color saturations and detection thresholds. To confirm the effects of color saturations, in subsequent experiments, we independently examined the effects of emotion and of color characteristics. We concluded that the previously reported increased temporal resolution was due to the confounding effect of color saturation, and not by the evoked emotion.     

Object temporal connotation

Recent studies show that what connotes an object is first of all a certain spatio-temporal structure. In this paper we describe some of the temporal features characterizing the temporal structure of objects: pre-existence, persistence, conservation of identity in spite of perceptive discontinuity, surviving changes in colour, size, and shape. We argue that time is an indispensable attribute for every type of object and briefly discuss the implication of this view with respect to a specific neuropsychological syndrome: unilateral spatial neglect.