The generality of outside-in processing routines in the analysis of form

In a previous study, Earhard and Walker (1985) showed that outer details of forms were more accurately reported than inner details. Although they suggested that this pattern might reflect a routinely applied outside-in processing strategy, their ability to generalize was limited by a reliance on small, single forms which occupied a fixed position in the visual field. To provide a more adequate assessment of generality of outside-in processing, a series of five experiments examined the discriminability of inner- and outer-line detail under a wide variety of conditions. Support for a general outside-in processing routine was obtained. More accurate reporting of outer detail was evident with large as well as small forms, with long and short exposure durations, and with trial-by-trial variations in the size and orientation of forms. Outer lines were also reported more accurately when a number of forms were presented simultaneously for inspection and under circumstances where error rates were low and reaction time procedures were employed. Evidence was presented to support the view that the more accurate discrimination of outer detail reflected the deployment of an attentional strategy.     

Independent processing of form, colour, and texture in object perception

Most investigations of object recognition have focused on the form rather than the material properties of objects. Nevertheless, knowledge of the material properties of an object (via its surface cues) can provide important information about that object's identity. In this study, we used Garner's speeded-classification task to explore whether or not the processing of form and the processing of surface properties are independent. In experiment 1, participants made length and width classifications in an initial form task. Participants were unable to ignore length while making width classifications, and were unable to ignore width while making length classifications. This suggests that the perception of length and the perception of width share common processing resources. In a subsequent task, we examined possible interactions between the processing of form and the processing of surface properties. In contrast to the findings with the form task, participants were able to ignore form while making surface-property classifications, and to ignore surface properties while making form classifications. This suggests that the form of objects and their surface properties are processed independently. In experiment 2, we went on to show that the two prominent surface-property dimensions of colour and texture can also be processed independently. In other words, participants were able to ignore colour while making texture classifications, and vice versa. Finally, in experiment 3, we examined the possibility that the stimuli and required responses that we used in experiment 2 were too categorical and thus not optimal for assessing whether or not colour and texture share common processing resources. Using a different stimulus set, participants were again able to ignore colour while making texture classifications, and vice versa. Taken together, these results provided convincing evidence that the separate ventral-stream brain regions identified for form, texture, and colour in a recent neuroimaging study (Cant and Goodale, 2007 Cerebral Cortex 17 713-731) can indeed function independently.     

Dynamic form perception in the bending

As a white hourglass moves across a black background, the middle appears to lag behind its true position, resulting in the apparent bending of the axis of the hourglass. No such distortion occurs with a black hourglass moving across a white background. The results of two experiments support a visual persistence hypothesis, as opposed to a latency hypothesis.     

Enhancing the perception of form in peripheral vision

Experiments are reported which show that the tachistoscopic presentation of a figure at the point of fixation makes salient the same figure where it occurs elsewhere in the visual field during the same flash. This induced saliency operates in all directions from the axis of gaze. If the eccentric figure is alone on a blank field the phenomenon is termed 'eccentric enhancement'. The induced saliency of figures that are laterally masked within horizontal strings of figures that lie off the fixation point is termed 'demasking'.     

Development of three-dimensional form perception

In three experiments with infants and one with adults we explored the generality, limitations, and informational bases of early form perception. In the infant studies we used a habituation-of-looking-time procedure and the method of Kellman (1984), in which responses to three-dimensional (3-D) form were isolated by habituating 16-week-old subjects to a single object in two different axes of rotation in depth, and testing afterward for dishabituation to the same object and to a different object in a novel axis of rotation. In Experiment 1, continuous optical transformations given by moving 16-week-old observers around a stationary 3-D object specified 3-D form to infants. In Experiment 2 we found no evidence of 3-D form perception from multiple, stationary, binocular views of objects by 16- and 24-week-olds. Experiment 3A indicated that perspective transformations of the bounding contours of an object, apart from surface information, can specify form at 16 weeks. Experiment 3B provided a methodological check, showing that adult subjects could neither perceive 3-D forms from the static views of the objects in Experiment 3A nor match views of either object across different rotations by proximal stimulus similarities. The results identify continuous perspective transformations, given by object or observer movement, as the informational bases of early 3-D form perception. Detecting form in stationary views appears to be a later developmental acquisition.     

Attentional biases in geometric form perception

This paper reports the operation of robust attentional bias to the top and right during perception of small, single geometric forms. Same/different judgements of successively presented standard and comparison forms are faster when local differences are located at top and right rather than in other regions of the forms. The bias persists when form size is reduced to approximately one degree of visual angle, and it is unaffected by saccadic eye movements and by instructions to attend to other reliably differentiating regions of the forms. Results lend support in various degrees to two of the possible explanations of the bias: (1) a static, skewed distribution of attentional resources around eye fixation; and (2) biased, covert scanning that commences invariably at the top and right of stim ulus forms. Origins of the bias in terms of possible left-hemispheric capacity for constructing representations of visual stimuli from parts, as well as in terms of reading experience and prevailing optic flow during locomotion through space are considered. Recent investigations of conditions under which the bias can be maintained or reduced are mentioned.     

An archer's perceived form scales the "hitableness" of archery targets

For skills that involve hitting a target, subsequent judgments of target size correlate with prior success in hitting that target. We used an archery context to examine the judgment-success relationship with varied target sizes in the absence of explicit knowledge of results. Competitive archers shot at targets 50 m away that varied in size among five diameters. Immediately after the arrow's release, its flight and landing were occluded and archers chose which of 18 miniature targets looked most like the distal target. Greater apparent size correlated with higher accuracy. In a second experiment, nonarchers merely aimed the bow (without an arrow) at varied targets. Apparent size was larger when the bow arm was stabilized than when it was not. Archery is seemingly an instance of affordance-based control: For an archer, the affordance of the target is the "hitableness" of its central regions, a property inclusive of his or her momentary, and perceptible, archery form. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Configural processing in the perception of eye-gaze direction

Traditional accounts of gaze perception emphasise the geometric or configural cues present in the eye; the position of the iris in relation to the corner of the eye, for example. This kind of geometric account has been supported, in part, by findings that gaze judgments are impaired in faces rotated through 180 degrees, a manipulation known to disrupt the processing of relations between facial elements. However, studies involving this manipulation have confounded inversion of the face context with inversion of the eye region. The effects of inversion might therefore have been caused by a disruption of the computation of gaze direction from the eye region itself and/or a disruption of the influence that face context might exert on gaze processing. In the experiment reported here we independently manipulated eye orientation and the orientation of the face context, and measured participants' sensitivity to gaze direction. Performance was severely affected by inversion of the eyes, regardless of the orientation of the face, whereas face inversion had no significant effect on gaze sensitivity. Previous reports of a face-inversion effect on gaze perception can therefore be attributed to inversion of the eye region itself which, we suggest, disrupts some form of configural or relational processing that is normally involved in the computation of eye-gaze direction.     

Levels of processing in speech perception

Four experiments are reported investigating previous findings that speech perception interferes with concurrent verbal memory but difficult nonverbal perceptual tasks do not, to any great degree. The forgetting produced by processing noisy speech could not be attributed to task difficulty, since equally difficult nonspeech tasks did not produce forgetting, and the extent of forgetting produced by speech could be manipulated independently of task difficulty. The forgetting could not be attributed to similarity between memory material and speech stimuli, since clear speech, analyzed in a simple and probably acoustically mediated discrimination task, produced little forgetting. The forgetting could not be attributed to a combination of similarity and difficutly since a very easy speech task involving clear speech produced as much forgetting as noisy speech tasks, as long as overt reproduction of the stimuli was required. By assuming that noisy speech and overtly reproduced speech are processed at a phonetic level but that clear, repetitive speech can be processed at a purely acoustic level, the forgetting produced by speech perception could be entirely attributed to the level at which the speech was processed. In a final experiment, results were obtained which suggest that if prior set induces processing of noisy and clear speech at comparable levels, the difference between the effects of noisy speech processing and clear speech processing on concurrent memory is completely eliminated.     

The influence of processing objectives on the perception of faces: An ERP study of race and gender perception

In two experiments, event-related potentials were used to examine the effects of attentional focus on the processing of race and gender cues from faces. When faces were still the focal stimuli, the processing of the faces at a level deeper than the social category by requiring a personality judgment resulted in early attention to race and gender, with race effects as early as 120 msec. This time course corresponds closely to those in past studies in which participants explicitly attended to target race and gender (Ito &Urland, 2003). However, a similar processing goal, coupled with a more complex stimulus array, delayed social category effects until 190 msec, in accord with the effects of complexity on visual attention. In addition, the N170 typically linked with structural face encoding was modulated by target race, but not by gender, when faces were perceived in a homogenous context consisting only of faces. This suggests that when basic-level distinctions between faces and nonfaces are irrelevant, the mechanism previously associated only with structural encoding can also be sensitive to features used to differentiate among faces.     

Local-to-global form interference in biological motion perception

Point-light walkers have been useful to study the contribution of form and motion to biological motion perception by manipulating the lifetime, number, or spatial distribution of the light points. Recent studies have also manipulated the light points themselves, replacing them with small images of objects. This manipulation degraded the recognizability of biological motion, particularly for local images of human bodies. This result suggests an interference of body form information in the local images with the body form analysis necessary for global biological motion recognition at the global level. We further explored this interference with respect to its selectivity for body orientation and motion. Participants had to either discriminate the facing direction (left/right) or the walking direction (forward/backward) of a global walker composed of local stick figures that could face left or right and either stand still or walk forward or backward. Local stick figures interfered stronger with the facing direction task if they were facing in the same direction as the global walker. Walking (forward/backward/static) of the stick figures influenced neither the facing direction task nor the walking direction task. We conclude that the interference is highly specific since it concerns not only the category (human form), but even the facing direction.     

Binocular summation in the perception of form at brief durations

Visual form identification at brief durations was studied under: (a) monocular presentation; (b) dichopic presentation where the same form was presented successively on noncorresponding areas; and (c) dichopic presentation where the same form was presented on corresponding areas simultaneously and successively. Form identification for noncorresponding area dichopic presentation was at the level to be expected from 2 independent chances to perceive. Both simultaneous and successive dichopic presentation on corresponding areas gave identification accuracy significantly above the level predicted by the assumption of independence. However, the binocular summation was not complete. When the same amount of energy entering the visual system in a binocular presentation was given in a monocular stimulation, the latter condition gave significantly better identification.