Size invariance in curve tracing

Subjects decided whether two dots were on the same curve or on different curves in patterns consisting of two curves and two dots in displays that had an exposure duration of 200 msec or that remained in view until the subjects' response. The overall size of the patterns was varied by a factor of two. Furthermore, across experiments, we manipulated the predictability of the size of the pattern on a particular trial. On half of the trials, the two dots were on the same curve; across these trials, the distance between the dots, along the curve, was manipulated systematically while the Euclidean distance between the dots was held constant. On the other half of the trials, the two dots were on different curves. The time to respond same increased monotonically as curve distance between the dots increased, suggesting that subjects mentally traced the curve in order to perform the task. The absolute size of the pattern had little or no effect on the response times, indicating that it was curve distance relative to the overall pattern size, rather than absolute distance, that controlled response times. Furthermore, expectancies about pattern size had essentially no effect on performance. Taken together, the results suggest that the rate of tracing is determined by various stimulus properties that covary with the overall size of the pattern on which tracing takes place, such as the distance between the traced curve and nearby distractor curves, or the curvature of the traced curve.     

Mental curve tracing with elementary stimuli

It has been proposed that certain spatial relations are determined by an operation, or "visual routine," that can trace along a boundary (Ullman, 1984). This proposal was supported by Jolicoeur, Ullman, and Mackay's (1986) finding that the time required to determine if two Xs are on the same curve increased monotonically with the separation of the Xs along that curve. In the present study the generality of the curve tracing hypothesis was explored across four experiments by using elementary stimuli that eliminated interweaving curves, displaced the fixation point away from the curves and target Xs, and provided a simple alternative to curve tracing--namely, determining whether or not the Xs fell on the same side of the figure. Stimuli consisted of two curves (150 degrees arcs) and two Xs, and each stimulus was presented for 150 ms. In Experiments 1 and 2, subjects were instructed to decide as quickly as possible if the two Xs fell on the same curve or on different curves. Even for these elementary stimuli, mean reaction time (RT) for same trials increased monotonically with the distance separating the Xs. Mean RT for different trials, however, decreased with the distance separating the Xs. In Experiments 3 and 4 alternatives to curve tracing were tested. For same trials the evidence strongly favored curve tracing. However, different trials were apparently solved on the basis of judgmental processes presumably operating in parallel with curve tracing. Curve tracing rates fluctuated across experiments and seemed to be partially governed by the width of the "pathway" provided for the trace.     

A gradual spread of attention during mental curve tracing

The visual system has to segregate objects that are relevant to behavior from other objects and the background, if they are embedded in a visual scene. This segregation process can be time consuming, especially if the relevant object is spatially extended and overlaps with other image components, but the cause of the delays is presently not well understood. In the present study, we used a curve-tracing task to investigate processing delays during the grouping of contour segments into elongated curves. Our results indicate that contour segments that need to be grouped together are labeled with visual attention. Attention gradually spreads from contour segments that were labeled previously to other contours that are colinear and connected to them. The contour-grouping task is completed as soon as attention is directed to the entire curve. We conclude that processing delays during contour grouping are caused by a time-consuming spread of visual attention.     

Predicting the shape of distance functions in curve tracing: Evidence for a zoom lens operator

Jolicoeur, Ullman, and MacKay (1986) showed that the time to confirm that two dots are on the same curve increases monotonically, but nonlinearly, as the curve distance between the two dots increases. These displays contained two curves and two dots. On same trials, the two dots were on the same curve (target curve), while the other curve served as a foil (distractor curve). The monotonically increasing effects of curve distance on response times for same trials suggested that the intervening curve segment was traced. In the present investigation of the source of the nonlinearity in these distance functions, it was hypothesized that differences in the distractor curves may have allowed a curve tracing operator with zoom lens properties to widen its receptive field while tracing parts of certain target curves. The wider receptive field may have allowed faster tracing over certain segments, owing to a reduced number of shifts required by the operator to scan the curve. The consequence of training certain segments of the curve more quickly than other segments of the curve would be a nonlinear effect of distance. A new set of stimuli was created for testing this hypothesis directly. Fairly linear distance effects were found for stimuli that contained a distractor curve that constrained the breadth of the postulated curve tracing operator, whereas stimuli that contained a distractor curve that could allow for a larger receptive field yielded nonlinear distance functions. The results are compared with the predictions of three quantitative models: pixel-by-pixel tracing; Jolicoeur, Ullman, and MacKay's (1991) bipartite operator; and a new zoom lens model, analogous to the zoom lens model of visual attention. The results were fit best by the latter model, in which tracing is accomplished by tracking the curve with a variably sized local operator.     

Psychometric properties of the Hooper Visual Organization Test

The psychometric properties of the Hooper Vsual Organization Test (VOT) have not been well investigated Here the authors present internal consistency and interrater reliability coefficients, and an item analysis, using data from a sample (N = 281) of "cognitively impaired" and "cognitively intact" patients, and patients with undetermined cognitive status. Coefficient alpha for the VOT total sample was .882. An item analysis found that 26 of the 30 items were good at discriminating among patients. Also, the interrater reliabilities for three raters (.992), two raters (.988), and one rater (.977) were excellent. Therefore, the judgmental scoring of the VOT does not interfere significantly with its clinical utility. The authors conclude that the VOT is a psychometrically sound test.     

Visual perception of dynamic properties: cue heuristics versus direct-perceptual competence

Constructivist and Gibsonian approaches disagree over the possibility of direct perceptual use of advanced information. A trenchant instance concerns visual perception of underlying dynamic properties as specified by kinematic patterns of events. For the paradigmatic task of discrimination of relative mass in observed collisions, 2 mathematical models are developed, 1 model representing a direct, invariant-based approach, and 1 representing a cue-heuristic approach. The models enable a critical experimental design with distinct predictions concerning performance data and confidence ratings. Although pretraining results were mixed, the invariant-based model was empirically confirmed after a minimal amount of training: Competence entails the use of advanced kinematic information in a direct-perceptual ("sensory") mode of apprehension, in contrast to beginners' use of simpler cues in an inferential ("cognitive") mode.     

Fading-figure tracing in Williams syndrome

Williams syndrome (WS) is a neurodevelopmental disorder characterized by severe impairment of visuospatial abilities. Figure-drawing abilities, which are thought to reflect visuospatial abilities, have yet to be fully investigated in WS. The purpose of the present study was to clarify whether drawing abilities differ between WS individuals and typically developing children (TD). We compared the performance of two groups of subjects (WS, mean age 16 years; TD, 5-6 years of age) using a fading-figure tracing task that requires subjects to trace a target figure that is gradually disappearing from a PC screen. Although the TD group exhibited clearly improved performance with long fading time, the WS group did not. Moreover, the TD group exhibited poor performance for figures with more than six angles, regardless of the figure type (e.g. closed or open), whereas the WS group exhibited generally poor performance for figures with more than five angles but relatively preserved performance for open figures. These findings indicate that a combination of decreased visuospatial span associated with incomplete development of visual scanning and disproportionate development of global processing may cause drawing disabilities in WS.     

Visual properties and memorising scenes: Effects of image-space sparseness and uniformity

Previous studies have demonstrated that humans have a remarkable capacity to memorise a large number of scenes. The research on memorability has shown that memory performance can be predicted by the content of an image. We explored how remembering an image is affected by the image properties within the context of the reference set, including the extent to which it is different from its neighbours (image-space sparseness) and if it belongs to the same category as its neighbours (uniformity). We used a reference set of 2,048 scenes (64 categories), evaluated pairwise scene similarity using deep features from a pretrained convolutional neural network (CNN), and calculated the image-space sparseness and uniformity for each image. We ran three memory experiments, varying the memory workload with experiment length and colour/greyscale presentation. We measured the sensitivity and criterion value changes as a function of image-space sparseness and uniformity. Across all three experiments, we found separate effects of 1) sparseness on memory sensitivity, and 2) uniformity on the recognition criterion. People better remembered (and correctly rejected) images that were more separated from others. People tended to make more false alarms and fewer miss errors in images from categorically uniform portions of the image-space. We propose that both image-space properties affect human decisions when recognising images. Additionally, we found that colour presentation did not yield better memory performance over grayscale images.     

Latent curve analysis

As a method for representing development, latent trait theory is presented in terms of a statistical model containing individual parameters and a structure on both the first and second moments of the random variables reflecting growth. Maximum likelihood parameter estimates and associated asymptotic tests follow directly. These procedures may be viewed as an alternative to standard repeated measures ANOVA and to first-order auto-regressive methods. As formulated, the model encompasses cohort sequential designs and allow for period or practice effects. A numerical illustration using data initially collected by Nesselroade and Baltes is presented.The authors wish to thank John Nesselroade for providing us the data for our illustration and Karen Paul and Connie Tilse for assisting in the data analysis. This research was supported by a grant (No. AG03164) from the National Institute on Aging to the senior author.     

Neuropsychological assessment with the Visual Gestalt Test: psychometric properties and differential diagnostic probabilities

The Visual Gestalt Test is a neuropsychological instrument developed for evaluation of learning and memory of visuo-spatial material. A revised strategy of scoring has motivated the present study, where data from 153 normal persons, 99 epilepsy patients, and 24 depressed patients are presented and compared. The Visual Gestalt Test is observed to discriminate between normal and diagnosed groups in several ways. Additionally it is found to discriminate between depressed and brain damage subgroups of patients. Data are presented in order to supplement previously published ways of scoring and norms. Practical guidelines for the clinical applications of the test are suggested as perspectives.     

Eye-hand interactions in tracing and drawing tasks

We report a preliminary analysis of the interactions between eye and hand during tracing and drawing of four simple shapes. Eye and hand movements were recorded using the ASL 504 system and the Flock of Birds system, respectively. During tracing, pen tip and eye were tightly coupled, with participants making a series of small saccades just in front of the moving pen, interspersed with periods of smooth pursuit. During drawing, saccades were fewer and larger and pursuit was less frequent. Observed eye-hand interactions suggested a bidirectional relationship between the eye and hand. These findings are explained in terms of the differing degree that the two tasks employ visual detail, external or internal cues and eye-hand coordination.     

Visual arguments

Three experiments investigated the use of verb argument structure by tracking participants' eye movements across a set of related pictures as they listened to sentences. The assumption was that listeners would naturally look at relevant pictures as they were mentioned or implied. The primary hypothesis was that a verb would implicitly introduce relevant entities (linguistic arguments) that had not yet been mentioned, and thus a picture corresponding to such an entity would draw anticipatory looks. For example, upon hearing ...mother suggested..., participants would look at a potential recipient of the suggestion. The only explicit task was responding to comprehension questions. Experiments 1 and 2 manipulated both the argument structure of the verb and the typicality/co-occurrence frequency of the target argument/adjunct, in order to distinguish between anticipatory looks to arguments specifically and anticipatory looks to pictures that were strongly associated with the verb, but did not have the linguistic status of argument. Experiment 3 manipulated argument status alone. In Experiments 1 and 3, there were more anticipatory looks to potential arguments than to potential adjuncts, beginning about 500 ms after the acoustic onset of the verb. Experiment 2 revealed a main effect of typicality. These findings indicate that both real world knowledge and argument structure guide visual attention within this paradigm, but that argument structure has a privileged status in focusing listener attention on relevant aspects of a visual scene.     

Visual evidence

Visual and other demonstrative evidence has become increasingly prevalent in American and other courtrooms in recent years. However, there have been relatively few experimental studies of the effects of this kind of evidence in legal settings. As a consequence, little is known about when and how it affects legal decision making. In this article, I survey the extant research, including studies of photographs, videos, computer animations, and PowerPoint displays. The research shows that visual evidence affects legal decisions in some circumstances but not in others. It also indicates that visual evidence sometimes enhances legal judgment by improving recall and understanding but sometimes impairs judgment by prompting undue emotional responses, cognitive and perceptual biases, and/or peripheral processing. The limitations of the research are discussed, and directions for future research are suggested.