Orientation tuning of shape from shading.

Four experiments were performed to assess the effect of different orientations and direction of lighting on the visual processing of shaded or bipartite disks. In the first two experiments, observers were presented with nine different shading orientations from 0 degree to 180 degrees. Targets were detected in a rapid and parallel fashion for shaded disks when the orientation of the shading gradient was not horizontal (90 degrees) or oriented at 67.5 degrees. Search asymmetries favoring the detection of "pock" targets over "ball" targets were found for all orientations. The search rates for bipartite disks were similar to the shaded disks at 0 degree, 22.5 degrees, and 90 degrees but not for intermediate orientations, and no search asymmetries were found. These differences suggest that shaded displays and bipartite displays are processed by different underlying mechanisms. The third experiment showed that the direction of the light source (left or right) had no influence on search asymmetries around the 90 degrees point. Shading gradient orientation affected magnitude estimates of depth in the fourth experiment. These experiments show that the visual system's "assumption" of overhead lighting is broadly tuned.

The face-inversion effect as a deficit in the encoding of configural information: direct evidence.

We report four experiments leading to conclusions that: (i) the face-inversion effect is mainly due to the deficits in processing of configural information from inverted faces; and (ii) this effect occurs primarily at the encoding stage of face processing, rather than at the storage stage. In experiment 1, participants discriminated upright faces differing primarily in configuration with 81% accuracy. Participants viewing the same faces presented upside down scored only 55%. In experiment 2, the corresponding discrimination rates for faces differing mainly in featural information were 91% (upright) and 90% (inverted). In experiments 3 and 4, the same faces were used in a memory paradigm. In experiment 3, a delayed matching-to-sample task was used, in which upright-face pairs differed either in configuration or features. Recognition rates were comparable to those for the corresponding upright faces in the discrimination tasks in experiments 1 and 2. However, there was no effect of delay (1 s, 5 s, or 10 s). In experiment 4, we repeated experiment 3, this time with inverted faces. Results were comparable to those of inverted conditions in experiments 1 and 2, and again there was no effect of delay. Together these results suggest that an 'encoding bottleneck' for configural information may be responsible for the face-inversion effect in particular, and memory for faces in general.

Children's use of triadic eye gaze information for "mind reading".

Five experiments examined children's use of eye gaze information for "mind-reading" purposes, specifically, for inferring another person's desire. When presented with static displays in the first 3 experiments, only by 4 years of age did children use another person's eye direction to infer desires, although younger children could identify the person's focus of attention. Further, 3-year-olds were capable of inferring desire from other nonverbal cues, such as pointing (Experiment 3). When eye gaze was presented dynamically with several other scaffolding cues (Experiment 4), 2- and 3-year-olds successfully used eye gaze for desire inference. Scaffolding cues were removed in Experiment 5, and 2- and 3-year-olds still performed above chance in using eye gaze. Results suggest that 2-year-olds are capable of using eye gaze alone to infer about another's desire. The authors propose that the acquisition of the ability to use attentional cues to infer another's mental state may involve both an association process and a differentiation process.

A neurological dissociation between shape from shading and shape from edges.

We studied the ability of a neurological patient, who has deficits in various aspects of form perception, to perform region segregation tasks requiring discriminations based on several image properties that are related to the three-dimensional structure of objects. The patient could discriminate the apparent three-dimensional structure and orientation of shapes defined by shading gradients, but could not make such discriminations for shapes in which edges were depicted as lines or as luminance discontinuities. These results suggest that the neural pathways that compute shape from shading gradients may be independent of those that compute shape based on edges, and, based on the patient's pattern of brain damage, they also indicate a relatively early functional separation in the requisite inputs.

The effect of dark and equiluminant occlusion on the interocular transfer of visual aftereffects.

Lehmkuhle and Fox [(1976) Vision Research, 16, 428-430] reported that interocular transfer (IOT) of a translational motion aftereffect (MAE) was greater if the non-adapting eye viewed an equiluminant field than if it viewed a dark field. They recommended equiluminant occlusion of the non-adapted eye when measuring IOT of aftereffects. We tested this proposal in three experiments. First, we assessed IOT with equiluminant and dark occlusion for three different classes of aftereffects. Although transfer was greater with equiluminant occlusion for the translational MAE, there was no significant difference in the amount of transfer for the tilt aftereffect or the contrast threshold elevation effect. Second, we tested the hypothesis that spuriously large IOT could be the result of an aftereffect from tracking eye movements in the non-adapting eye. When potential tracking movements were reduced by using rotating spokes, a rotating spiral or contracting concentric circles, there was a corresponding reduction in the occlusion-dependent transfer. Third, we found that luminance shifts had no influence on the amount of transfer when all contours were eliminated from the non-adapting eye. We conclude that the type of occlusion used for measuring IOT of the translational MAE is important only when visible contours in the non-adapting eye contribute to the adapting process.

The aftereffect to relative motion does not show interocular transfer.

The motion aftereffect is strongest after viewing a moving field embedded in a patterned stationary surround, which suggests that relative motion is an important signal for its generation. The contribution of relative motion to binocular aspects of the motion aftereffect was assessed. Subjects viewed uniformly moving random dots surrounded by a stationary random-dot annulus. These displays could be presented in a variety of combinations to each eye separately or to both eyes, during adaptation and test. It was found that, although the presence of relative motion during adaptation significantly extended the duration of the monocular motion aftereffect, it did not augment interocular transfer. The presence of stationary surround contours in the nonadapting eye did not influence the aftereffect in the adapting eye. The enhancement provided by stationary surround contours is largely dependent on their presence during adaptation. The presence or absence of surround contours during the test phase did not influence the duration of the aftereffect. These findings are consistent with previous suggestions that the motion aftereffect is, in part, the result of adaptation to relative motion that occurs relatively early in the visual pathway-before binocular integration.

Text-contingent color aftereffects: a reexamination.

Five experiments reexamined color aftereffects contingent on the semantic properties of text (Allan, Siegel, Collins, & MacQueen, 1989). The influence of different assessment techniques and the effect of eye movements and overlapping contour information on the induction of color aftereffects by word and nonword letter strings were determined. Experiment 1 showed that no aftereffect was found when a traditional method of assessing color aftereffects was used. Experiments 2 and 4 demonstrated color aftereffects for both words and nonwords, but only when subjects fixated the same locus during induction and testing and only when assessed with the technique described by Allan et al. (1989). If, however, eye movements were made during induction, no color aftereffect was obtained (Experiment 3). Induction to nontext patterns with properties similar to those of text but with fewer overlapping contours resulted in a strong color aftereffect (Experiment 5). These results suggest that the color aftereffect contingent on text is very weak and is not dependent on semantic factors, but that it is a product of induction to local color and orientation information.

An examination of the intramodal and intermodal behavioral consequences of long-term vibrissae removal in rats.

An assessment was made of the effects of long-term tactile restriction by bilateral removal of the mystacial vibrissae from an early age on the subsequent somatosensory capacities of rats (i.e., the intramodal consequences) as well as its effects on visual and spatial capacities (i.e., the intermodal consequences). Rearing environment (enriched vs. normal) and method of vibrissae removal (cauterization of follicles vs. plucking) were examined to determine specific factors that m might influence the effect of vibrissae removal. Early, long-term tactile restriction had significant intramodal and intermodal consequences. Dewhiskered rats showed attenuated orientation to tactile stimuli presented to their mystacial pads and enriched-reared rats whose vibrissae follicles had been cauterized showed increased orientation to visual stimuli. Manipulation of early somatosensory signals had no impact on the development of certain spatial and precise manipulatory skills. These data provide limited evidence for theories of modality interdependence and yield basic information concerning the role of the mystacial vibrissae in the behavior of the rat.

Results of treatment of cancer of the cervix in Wellington 1980-4.

A review was undertaken of all 115 women with invasive carcinoma of the cervix referred for treatment to the Wellington regional centre during the period 1980-4. In comparison with the previous five year period, there were 31 (37%) more patients, and a higher proportion of patients had stage I and II disease. The incidence of disease was significantly greater in Maori compared with nonMaori. Treatment was by various combinations of surgery and radiation according to agreed protocols. The actuarial survival at five years was 73% for the whole group, 89% for 64 stage I patients, 65% for 28 stage II patients and 45% for 19 stage III patients. The actuarial risk of a major treatment complication within the first five years was 8.8%. These results confirm that regional centres in New Zealand employing a multidisciplinary approach to patient assessment and treatment can achieve high cure rates with an acceptable incidence of treatment complications. However, prevention of the disease by effective cervical screening programmes should remain an objective of health services in New Zealand.

Arteriovenous malformations of the brain: outcome of conventional radiotherapy in the management of 33 cases.

Thirty three patients with inoperable arteriovenous malformations of the brain received conventionally fractionated megavoltage photon radiotherapy. The dose varied between 30.00 wand 50.00 Gy with a median of 40.00 Gy. Treatment was not associated with any significant morbidity. Follow-up ranged from 16 months to 148 months, with a median of 79 months. The projected 5-year survival is 92% and rebleed-free survival 78%. There was a trend of increased bleed-free survival for doses greater than 46.00 Gy.

Development of defensive burying in Rattus norvegicus: experience and defensive responses.

Rats (Rattus norvegicus) deprived of the opportunity to interact with particulate matter until they were young adults engaged in defensive burying after they were shocked by a wire-wrapped dowel in a test chamber that held bedding material. Interacting with a particulate substrate during development is not necessary for the expression of defensive burying in adulthood. However, interacting with a particulate substrate early in the rats' lives did have a substantial effect on the emergence and maintenance of burying behavior. Defensive burying developed at a later age and declined at an earlier age in rats maintained on wire mesh from birth until testing than it did in rats raised until weaning on bedding and housed on mesh thereafter. Because defensive burying is a complex, flexible, yet reliable response sequence that cannot be performed without the appropriate substrate, it has considerable potential as a model for the study of the development of species-specific defense responses.

Effects of intertrial reinforcers on rats' timing behavior.

Two experiments were conducted to assess the effects of non-contingent intertrial interval (ITI) reinforcers on rats' discrimination of duration. In the first experiment, rats' discrimination of a 2 vs. 8 s of light was significantly disrupted when reinforcers were presented in the ITI. Disruption was not different on short (2 s) and long (8 s) trials. The second experiment showed that this disruptive effect was not specific to trials preceded by ITI reinforcers; responding on empty ITI trials run in the same session as ITI-reinforcer trials was also disrupted. This disruption however was not as great as on the ITI-reinforcer trials. The results of these experiments show that ITI reinforcers affect timing discriminations in much the same way they affect classical conditioning and delayed matching to sample. However, detailed examination of the results suggests that the deleterious effects of ITI reinforcers in these different paradigms might be produced by different rather than the same mechanism. The results also support the conclusion that pre-trial reinforcement "priming" produces disruption rather than facilitation in complex tasks.

Intersensory coordination and the effects of early sensory deprivation.

The effect of early visual deprivation on the ability of dark- (DR) and light-reared (LR) rats to learn temporal discriminations involving sounds and lights and to abstract the intersensory correspondence involving duration from initial modality-specific training was examined in this study. While visually inexperienced DR rats were somewhat less successful in acquiring an initial discrimination involving visual events and responding to a rule reversal per se, they were as effective as their visually experienced LR counterparts in demonstrating cross-modal transfer (CMT) to signals in a new modality. The results revealed by the investigation are discussed in terms of the consequences and lack of consequences of the manipulation of early visual experience on the ontogeny of intersensory perceptual development in mammals.