A rudimentary touch input device for visual displays

An inexpensive and simple device that can be fitted to existing computer visual display units and that gives a limited touch input capability is described. Small transparent acrylic pieces are held in front of the CRT by stiff wires attached to microswitches. The device has proved useful in the provision of computer-assisted instruction for young children.     

A device for inverting the visual field of animals

A device for inverting the visual field of small animals is described. Binocular lenses are mounted in a lightweight, aluminum frame which, in turn, is secured to a surgically attached, dental acrylic skull cap. The construction of the device, and its usefulness when simultaneous electrophysiological recordings are desired, is described by illustrating the details of fabricating such a device for a cat.     

A simple device for detecting departures from visual fixation

A device for detecting departures from visual fixation is described. The principle is to present control targets to one or both eyes at the projected position of the blind spot. When fixation is maintained the control target or targets are not seen. Departures from fixation manifest themselves by the reappearance of the target or targets in the visual field. The system allows approximately 1 deg of movement or less away from the fixation point in either direction.     

A simple technique for lateralizing visual input that allows prolonged viewing

A simplified technique is described for obtaining lateralization of visual input with prolonged viewing. This technique is based on the presence of constant normal lateral limits for horizontal rotation of the eyes with reference to the head. With head movement prevented by use of a standard bite bar, and the eyes rotated to the left and held at their lateral limit, the temporal half of the visual field of the left eye may be used for lateralized input to the right hemisphere or vice versa for input to the left hemisphere. Any form of visual stimuli or visually monitored task can be used if confined within one of the extreme temporal hemifields. In comparison to previous methods, this technique is technically simple, inexpensive, without significant risk or discomfort to the subject, readily applicable to normal and various brain-lesioned subjects, and permits prolonged in-depth viewing. An alternative version of this technique uses a stabilized spectacle frame fitted with adjustable central occluders set to allow vision through only one or both of the extreme temporal hemifields.     

The use of contact lenses for the lateralisation of visual input in man.

This research demonstrates the use of a new method of investigating lateralised hemisphere functions. Specially designed contact lenses were used, which directed visual input to either the left or the right cerebral hemisphere. These lenses are an advance on previous methods used in investigating hemisphere function in that they enable the subject to react to stimuli without restrictions on movement and without time limitations on the exposure of stimuli. Investigations of language and visual-spatial functions showed that the lenses appeared to be very effective in lateralising verbal and spatial information.     

Mobility of normal observers under conditions of reduced visual input.

The importance in mobility performance of the rate of presentation of visual information, binocular versus monocular vision, the use of multiple rather than single reference points, and local motion parallax was investigated in two experiments. In each experiment ten subjects walked a triangular mobility course in a totally darkened room; the only visible targets were light emitting diodes (LEDs), mounted on poles, at the apices of the triangle. The LEDs were mounted so that one or two could be used in a trial; if two were used the distance between them was varied horizontally (in experiment 1) and vertically (in experiment 2). The subjects walked around the course under a range of conditions, including two 'optimal trials' in full light. The LEDs were flashed for 1 ms at frequencies of 0.5, 1 and 5 Hz in experiment 1 and at 1 and 5 Hz in experiment 2. Mobility was measured with the use of an ultrasonic locator system which measured the subject's position on the course 10 times per second. The mean velocity of the subject in traversing the course was significantly reduced when the flash rate was slower, when the subject had one eye occluded, or when there was only one LED on the pole; when the spacing between the LEDs was varied, either vertically or horizontally performance was unaffected. These results imply that the frequency of updating of visual information is important in determining mobility performance, as are binocular cues, but that local motion parallax is not important. The number of LEDs on each pole had a significant effect on mobility performance an 'object' (two lights) gave more information than a point reference.     

Early modulation of visual input: A study of attentional strategies

Despite agreement among many attentional theories that processing resources are limited and allocated according to task demands, controversy continues about the locus of selectivity. Studies of spatial orientation of attention suggest an early effect. These results, however, can be explained instead by effects of decision processes. The present study avoids this difficulty by directly manipulating attention in a dual-task paradigm and by using SDT to dissociate sensory tuning from criterion shifts. Ten subjects judged whether two lines to the left of fixation were the same or different in length; they also judged two lines presented simultaneously to the right. In a given block of 64 trials, the subject was to allocate 80%, 50%, or 20% of attention to one pair of lines and the rest to the other. On every trial, the subject judged both pairs. Results showed that d' increased from 0.77 with 20% allocation to 1.69 with 80%, indicating that sensitivity is modulated by attentional instructions. These results are predicted quantitatively by Luce's sample-size model.     

Semantic effects in visual word detection with visual similarity controlled

In three experiments, subjects searched through word lists for a single target word. Search was faster when the target word belonged to a different semantic category from that of the background words with visual similarity controlled. This semantic effect increased with number of items to be searched through, and it obtained whether the target was cued visually or verbally. Semantic homogeneity within the background also speeded search, but only when subjects had no prior knowledge of the nature of a list. Several models of the semantic effect are described. All contrast the encoding of physical identity with the encoding of semantic attributes, but they differ in ascribing the effect to: (1) the relative access times for these codes, (2) the power of the codes in dealing with multiple comparisons, or (3) the attentional demands of comparison using different levels of code.     

The coordination of visual and tactual input in infants

Traditionally it has been taught that “touch teaches vision” in ontogeny. Recent experiments have shown that in judgment situations vision dominates touch, a finding that has been taken to weaken the traditional argument. The force of the finding is vitiated to some extent by the functional dominance of touch. Developmental experiments show that initially in ontogeny vision is functionally dominant, strengthening the case against the traditional argument.     

Transfer of visual information after unilateral input to the brain

Visual callosal connections are more numerous and widespread in the association areas than in the primary visual cortex and adjoining visual areas. In keeping with this, the amount of "wrong" ipsilateral visual field that is represented in the various cortical areas of primates and cats increases as one goes from primary visual cortex to extraoccipital areas. Therefore it can be argued that transfer of unilaterally presented visual stimuli occurs mainly at the temporal and parietal cortical level.     

A device for teaching the theory of technique.

The usefulness of comparing dream psychology and neurosis psychology is demonstrated in the teaching of a course on the theory of technique at the Pittsburgh Psychoanalytic Institute. Candidates are assigned the task of writing a five-minute segment of free associations using assigned background material, resistances to be demonstrated, and assigned current and past conflicts. The candidates then present their free associations to the class for analysis. Explication of educational and developmental issues is given.     

Effects of input device and motion type on a cursor-positioning task

Many studies have investigated the performance of using nonkey-board input devices under static situations, but few have considered the effects of motion type on manipulating these input devices. In this study comparison of 12 mens' performance using four input devices (three trackballs: currently used, trackman wheel, and erectly held trackballs, as well as a touch screen) under five motion types of static, heave, roll, pitch, and random movements was conducted. The input device and motion type significantly affected movement speed and accuracy, and their interaction significantly affected the movement speed. The touch screen was the fastest but the least accurate input device. The erectly held trackball was the slowest, whereas the error rate of the currently used trackball was the lowest. Impairments of the random motion on movement time and error rate were larger than those of other motion types. Considering objective and subjective evaluations, the trackman wheel and currently used trackball were more efficient in operation than the erectly held trackball and touch screen under the motion environments.