Object Identification Task Research Articles

Spatial frequencies in short-term memory for faces: a test of three frequency-dependent hypotheses.

Spatial frequency manipulations have been shown to have significant utility in ascertaining the various types of information that might be important in object identification and recognition tasks. This utility suggests that, given some mapping between ranges of spatial frequencies and different types of psychological information, it should be possible to examine the roles of these different types of psychological information by way of spatial frequency manipulations. One potential problem, however, is that there is no well-specified, unambiguous mapping between the distinctions in the frequency domain and the distinctions in the informational domain. Three experiments provide tests of three general hypotheses regarding the ways in which different spatial frequencies might map to different information in facial perception and memory tasks: (1) the low-frequency dominance hypothesis, which proposes that low-frequency information should be superior (to high-frequency information) as a cue to perception and memory; (2) the distinct informational roles hypothesis, which holds that high spatial frequencies should carry featural information while low spatial frequencies should carry information about the configuration of those features; and (3) the task-dependent information hypothesis, which suggests that high-frequency information should be best suited to discrimination tasks while low-frequency information should be best suited for recognition tasks. Results generally contradict the first two of these hypotheses, while providing support for the third. Implications with regard to the various issues related to the mapping between spatial frequencies and the informational content of faces, as well as the need to consider important interactions among perceptual and memory processes, are discussed.

Performance of 5-Year-Old Children on Seven Visual Perceptual Tasks in Relation to Neonatal Ultrasound Abnormalities

We investigated whether neonatal brain damage can give rise to visual perceptual deficits, in addition to the well-documented impairments in visual acuity. To this end, forty-one children (age 5.02 to 5.89 years) were given four visual object identification tasks and three visuo-constructive tasks. These subjects were neonatal at risk owing to prematurity or birth asphyxia. From neonatal ultrasound scans, the occurrence of intracranial hemorrhage (ICH, N = 17), periventricular leukomalacia (PVL, N = 15), and/or white matter damage due to either of these conditions (WMD, N = 9) was determined for each subject. Scans were normal in fourteen of them. The number of subjects performing at or below Pc10 of same-age normal children was significantly above 10% for each task (range 27% – 49%). This was still true when mental instead of chronological age was used for comparison, as shown by the results of nine subjects for which intelligence data were available. This high incidence of impairment is not attributable to loss of visual acuity, since grating acuity was reduced in only four subjects (14 – 19 cycles deg−1). The frequency of scores < Pc10 correlated significantly with WMD in six tasks, with PVL in 4 tasks, but not with ICH. We conclude that neonatal at risk children are more likely to develop impaired visual perceptual skills, independent of mental disability and visual acuity loss. On ultrasound permanent white matter abnormalities are most strongly associated with visual perceptual deficit, whereas intracranial hemorrhage is unrelated.

Animal-Assisted Enhancement of Speech Therapy: A Case Study

SUMMARYThis report assesses the impact of Animal-Assisted Therapy (AAT) as it applies to speech/language pathology. It is a case study of a 72-year-old female who had experienced multiple strokes and other related medical complications. Treatment utilizing two canine therapists, Charlie and Josh, increased one-word answers and object identification tasks, as well as verbalization behaviors in the subject.

Reexamining the Snodgrass and Corwin 1988 picture identification norms.

Snodgrass and Corwin (1988) provided a database of 150 fragmented pictures identified by subjects only 35% of the time. However, recent research by Koch, Abbey, and Schmidt in 1995 with these pictures has yielded higher identification rates. The present study examined the difference in identification rates between Koch, et al., 1995 and Snodgrass and Corwin in 1988. 85 subjects were given 25 min. to identify all 150 pictures from Snodgrass and Corwin. Of the 150 pictures, 95 were identified more than 35% of the time. Since Snodgrass and Corwin used an implicit-learning task while the present study used an object-identification task, the present findings suggest that identification rates may be specific to the type of object-recognition task employed.

Children's ambiguous utterances: a re-examination of processing limitations on production.

The ability to convey the optimal amount of information during conversation is a fundamental aspect of language use. In this study the relationship between children's failures to produce unambiguous utterances and the mental effort demands of the communication task was investigated. Five-, six-, seven- and nine-year-old children performed a message production task and a finger-tapping task both separately and simultaneously. The decrease in finger-tapping frequency during the simultaneous performance was used as an estimate of effort demands of the message production task. Working memory capacity was assessed by means of a spatial memory test and an object features identification task. Children's intuitions about message adequacy were recorded in two message evaluation tasks. By age six children proved to be able to select the relevant information when they were explicitly asked to do so, indicating that effort demands of the communication task did not exceed their computational resources. However, results suggested that the relative effort requirements of the communication task decrease with increasing age. These findings support a performance theory of communication development in which effort demands are a determinant of children's message adequacy.

A MULTILEVEL FUSION APPROACH TO OBJECT IDENTIFICATION IN OUTDOOR ROAD SCENES

The task of object identification is fundamental to the operations of an autonomous vehicle. It can be accomplished by using techniques based on a Multisensor Fusion framework, which allows the integration of data coming from different sensors. In this paper, an approach to the synergic interpretation of data provided by thermal and visual sensors is proposed. Such integration is justified by the necessity for solving the ambiguities that may arise from separate data interpretations. The architecture of a distributed Knowledge-Based system is described. It performs an Intelligent Data Fusion process by integrating, in an opportunistic way, data acquired with a thermal and a video (b/w) camera. Data integration is performed at various architecture levels in order to increase the robustness of the whole recognition process. A priori models allow the system to obtain interesting data from both sensors; to transform such data into intermediate symbolic objects; and, finally, to recognize environmental situations on which to perform further processing. Some results are reported for different environmental conditions (i.e. a road scene by day and by night, with and without the presence of obstacles).

Use of captions and other collateral text in understanding photographs

This research explores the interaction of textual and photographic information in image understanding. Specifically, it presents a computational model whereby textual captions are used as collateral information in the interpretation of the corresponding photographs. The final understanding of the picture and caption reflects a consolidation of the information obtained from each of the two sources and can thus be used in intelligent information retrieval tasks. The problem of building a general-purpose computer vision system withouta priori knowledge is very difficult at best. The concept of using collateral information in scene understanding has been explored in systems that use general scene context in the task of object identification. The work described here extends this notion by incorporating picture specific information. A multi-stage systemPICTION which uses captions to identify humans in an accompanying photograph is described. This provides a computationally less expensive alternative to traditional methods of face recognition. A key component of the system is the utilisation of spatial and characteristic constraints (derived from the caption) in labeling face candidates (generated by a face locator).

Effects of altering communicative input for students with autism and no speech: Two case studies

Individuals with autism and severe mental retardation typically display deficits in both communicative input and communicative output skills. Comprehension of spoken input may be particularly challenging for individuals with autism, for a number of reasons. This paper presents two case studies examining the impact of varying the form of communicative input on behavior management targets as well as performance on an object identification task. Both cases involved students with autism and no speech. One student responded with poor task performance and high frequencies of self-injury to spoken communication but not to gestures alone or gestural plus spoken communication. The other student displayed a similar pattern of task performance and showed an increased tendency toward disruptive behavior in response to spoken or spoken plus gestural communication only in high-stress situations. Program modifications (changes in the communication approaches of these students' communicative partners) are described. It is suggested that the impact of spoken communicative input on task performance and behavior management targets of individuals with autism be probed in cases where more straightforward programming issues have been addressed with only limited success.

From phenomena to models

Abstract Over the past ten years there has been a dramatic expansion in the number of empirical studies concerned with the phenomena of neglect: for instance, there has been research into the systematic, directional errors made by neglect patients in line bisection, the omissions made in line cancellation tasks, the misidentifications in reading and object identification tasks, the errors made in copying and drawing from memory, the denial of neglect (anosognosia), and so forth. This work, whilst welcome, has led to a burgeoning amount of empirical detail that needs to be digested by any researcher coming into the field. In addition, much of the work has suggested that, within the general syndrome of neglect, patients can differ quite strikingly from one another. There are now well-documented dissociations between (for example) patients whose neglect is dependent on visual feedback and those whose neglect is dependent on kineasthetic feedback concerning the position of the limb in space (e.g. Tegner & Lev...

Ambiguity reduction by relaxation labeling

A new relaxation labeling algorithm for a general n-node/ m-label system is developed and its theoretical as well as application aspects are analyzed. The convergence properties of the new relaxation algorithm are presented. Physical interpretations of the mathematical terms are discussed. Finally, an experiment of applying the new relaxation labeling algorithm to perform an object identification task in an intelligent robotic system with two cameras, is described.

Parts in object concepts: Experiments with artificial categories

Previous research has demonstrated that basic-level categories are associated with the parts of objects. Five experiments were conducted to investigate whether this correlation is caused by a psychological principle that requires basic concepts to have common parts. This hypothesis was investigated in the experiments by separating part and nonpart information in artificial categories. Basic-level structure was measured in two ways: as the level with the highest ratio of within-category similarity to between-category similarity, and as the level with the fastest categorization time in an object-identification task. The results revealed that basic-level structure could be found in categories that did not have parts in common. Furthermore, nonpart information, such as size, color, and texture, could both enhance the basic level and eliminate the basic-level advantage, depending on whether the nonpart information was consistent with or contradicted the part information. These results suggest that, psychologically, parts are neither necessary nor sufficient to form a basic level.

Robust estimation of surface curvature from deformation of apparent contours

Surface curvature along extremal boundaries is potentially useful information for navigation, grasping and object identification tasks. Previous theories have shown that qualitative information about curvature can be obtained from a static view. Furthermore, it is known that for orthographic projection, under planar viewer-motion, quantitative curvature information is available from spatio-temporal derivatives of flow. This theory is extended to arbitrary curvilinear viewer-motion and perspective projection. It is shown that curvatures can actually be computed this way in practice, but that they are highly sensitive to errors in viewer-motion estimates. Intuitively, relative or differential measurements of curvature might be far more robust. Rather than measuring the absolute deformation of an apparent contour, differential quantities depend on the rate at which surface features are swept over an extremal boundary as the viewer moves. It is shown that, theoretically, such differential quantities are indeed far less sensitive to uncertainty in viewer-motion. Ratios of differential measurements are less sensitive still. In practice, sensitivity is reduced by about two orders of magnitude, representing a significant step in the development of practical techniques for robust, qualitative 3D vision.

Positron emission tomographic measurements of pulvinar activity during an attention task

Positron emission tomographic scans were recorded from human subjects following an object-identification task, one version of which required attentional selection and the other version of which did not. In one experimental session, the attention-demanding displays were presented in the left visual field and the nonattention displays were presented in the right visual field. In a second session, the sides of the displays were reversed. Analysis of the scans indicated that, averaged across the 2 sessions, the pulvinar showed greater glucose uptake when it was contralateral to the display of the selective attention task than when it was contralateral to the display of the nonattention task. The pattern of the data indicated that the degree of the attention task effect on pulvinar glucose uptake may differ between the hemispheres. In view of known connections between the pulvinar and cortical areas that mediate object identification, the present finding suggests that the pulvinar operates interactively with these cortical structures when an identification process demands selective attention.

Signal detection analysis of ethanol effects on a complex conditional discrimination

The effects of ethanol on a conditional object identification task were investigated using an operant analog of Signal Detection Analysis. Water and three doses of ethanol (0.40, 0.75 and 1.5 g/kg) were orally administered on three separate occasions to three adult squirrel monkeys. Significant discrimination impairment as a function of increasing ethanol dose was observed. At the 1.5 g/kg dose, impairment extended to nonspecific effects, with subjects ceasing to respond early into the session. Subsequent signal detection analyses revealed that the reduction in performance resulted from losses in discriminability. Response bias was found to change unpredictably and independently of ethanol administration. Reaction time measures also showed no changes except a moderate, nonsignificant, facilitation in speed at the lowest (0.40 g/kg) dose. Taken together, these data suggest that ethanol acts to impair complex, or cognitive, performance by disrupting current sources of stimulus control within the range of doses tested.

Effect of background information on object identification.

Previous research using briefly presented displays has indicated that objects in a coherent scene are easier to identify than are objects in incoherent backgrounds. Of interest is whether the identification of the target object depends on the identification of the scene or the identification of other diagnostic objects in the scene. Experiment 1 indicated objects are more difficult to identify when located in an "episodically" inconsistent background even when the same diagnostic objects are present in both inconsistent and consistent backgrounds. Experiment 2 demonstrated that the degree to which noncued (cohort) objects are consistent with the target object has no effect on the object identification task. Experiment 3 showed consistent episodic background information facilitated object identification and inconsistent episodic background information did not interfere relative to "nonsense" backgrounds roughly equated on visual characteristics. Implications for models of scene perception are discussed.

Effect of background information on object identification.

Previous research using briefly presented displays has indicated that objects in a coherent scene are easier to identify than are objects in incoherent backgrounds. Of interest is whether the identification of the target object depends on the identification of the scene or the identification of other diagnostic objects in the scene. Experiment 1 indicated objects are more difficult to identify when located in an "episodically" inconsistent background even when the same diagnostic objects are present in both inconsistent and consistent backgrounds. Experiment 2 demonstrated that the degree to which noncued (cohort) objects are consistent with the target object has no effect on the object identification task. Experiment 3 showed consistent episodic background information facilitated object identification and inconsistent episodic background information did not interfere relative to "nonsense" backgrounds roughly equated on visual characteristics. Implications for models of scene perception are discussed.

Classification quality assessment for a generalized model-based object identification system

An object recognition system based on global features and nearest neighbor matching is extended and enhanced using classification quality assessment methodology. For quality assessment, a classification decision is processed at two levels. The first is to reject options that are not contained in the model database. The second is to identify the likelihood of error for classifications of known objects. Both stages are based on empirically determined thresholds of measures that are generated solely from the system's a priori knowledge, exploiting the known characteristics of both physical object space and feature space. Results are presented for a standardized object identification task, with a set of six similar known objects, and four unknown objects. It is shown that objects outside the model database are effectively rejected and that the accuracy of known object identifications is increased by rejecting views of low classification quality. >