Separating signal and noise in vibrotactile devices for the deaf.

This paper briefly reviews a series of experiments demonstrating that a sound-to-touch transform of signal and noise may be perceptually separated by providing tactile cues for sound localization. Following this, three experiments are reported in which it is shown that such stereotactile cues are available if two vibrotactile devices (Minifonators, produced by Siemens Co. Ltd.), are used instead of one. With this system, subjects were able to attend to a target signal (male voice) in white noise and when a female voice was presented simultaneously. This ability depended upon a sufficient spatial separation of the target and noise in acoustic space. These findings appear to have applications in the design of tactile hearing aids and cochlear implants when used in noisy environments or when more than one sound is present.

Effects of a summer preview program of study skills and basic science topics on the academic performance of minority students.

A summer preview program was designed to enhance the academic performance of minority students in medical school. In the five-week program the students met from 8:00 AM to noon, five days a week. The two components of the program were study skills and selected basic science topics deemed critical for success in the first year.This paper is an analysis of three years (1980 to 1982 inclusive) of the program. Only three of the 14 participating minority students failed to complete the requirements of the first year of the curriculum. In contrast, nine of the 11 nonparticipating minority students did not complete the requirements for the first year. The conclusion is that the program can enhance the academic performance of minority students in the first year of the medical school curriculum.

Can passive touch be better than active touch? A comparison of active and passive tactile maze learning.

In a comparison of the performance of active (n=15) and passive (n=15) mechanically yoked subjects who learned their way through a tactile maze, it was shown that active subjects mad more errors and took a greater number of trials to reach criterion than did passive subjects. In addition, the difference between active and passive performance was largely accounted for by the greater number of repeated errors made by active subjects. In a second experiment it was found that the poorer performance of active subjects could be attributed to the interfering effects of decisions about which way to move. However, the responsibility for the production of movement had no effect on performance. it was argued that the results reflected limits to the cognitive system, not the haptic system.

Critical periods for the transmission of tactual information.

There is good evidence for critical periods in the development of sensory processes (particularly vision and hearing) and language functions. If appropriate experience is absent during these critical periods, later performance is impaired. This principle is of importance to designers of devices which use the skin as an alternative channel of communication for the blind of the deaf. The implications are that: (a) Some promising devices may have been prematurely abandoned because they were tested on adults rather than children. (b) Tactile devices should be evaluated in studies with children who have not yet passed through the critical period for touch and language development. It is argued that early exposure to a tactile transformation of speech (for example) might provide the profoundly deaf with two significant advantages. Firstly, early exposure increases the chance that the cutaneous system will develop neural connections appropriate to the handling of the transformed speech signal. In other words, tactile sensitivity can be optimized. Secondly, early exposure to language as a process associated with the cutaneous system (rather than the auditory system) might favour the development of cortical connections consistent with the sensory substitution system. Such plasticity might no longer exist when the critical period has passed.

The pharmacy of ceftazidime.

The stability of ceftazidime for injection in the dry state and after reconstitution with water for injections was determined. Compatibility of ceftazidime for injection with lignocaine hydrochloride injection (1.0% w/v) and several commonly used intravenous fluids was tested, Ceftazidime for injection was found to be essentially stable in the dry state and may be stored at 25 degrees C. In solution, loss of potency occurs slowly; it was concluded that, if stored at room temperature, vials reconstituted with either water for injections or lignocaine hydrochloride injection (1-0% w/v) should be used within 6 h of preparation and dilute solutions in intravenous fluids should be used within 24 h of preparation (6 h for sodium bicarbonate solution).

The nonequivalence of abrupt and diffuse illusory contours.

A distinction is drawn between diffuse regions of apparent brightness and illusory, but abrupt, brightness gradients. Differences between the two phenomena are sufficient to disqualify conclusions about one based on observations about the other. It is suggested that diffuse contours may be attributable to peripheral mechanisms while sharp contours may be central or cognitive in origin.

Sensory substitution and the design of an artificial ear.

This paper is concerned with attempts at sensory substitution and in particular with devices that have been designed to substitute for hearing by using the skin as an alternative channel of communication. A review of the literature suggests that the failure or limitations of tactile substitution systems are due, not to the inadequacy of the skin's perceptual processing capacity, but to inappropriate displays, ineffective training methods, or insensitive testing techniques. Specifically, displays have been artificial in that they have typically failed to preserve the information relevant to the modality for which they are supposed to substitute. Furthermore, certain false assumptions and misconceptions have been manifest in testing techniques which have not taken into account the way in which perceptual processes normally develop and operate. The result has been that some important evidence has been ignored or has gone unnoticed and that some promising devices have been prematurely abandoned. In the final section of the review, some suggestions are made concerning the design, application, and evaluation of an artificial ear.

Computerized analysis and duplication of mandibular motion.

A new digital system has been devised to analyze and duplicate jaw motion. The arrangement of the electronic system offers a range of versatility which includes graphic as well as numerical data analysis. The duplicator linkage is identical to the sensor linkage which, together with an accurate model transfer system, results in an encouraging level of accuracy in jaw-motion duplication. The data collected from normal subjects should offer some new knowledge in the normal motions of the mandible as well as establish a reference for comparison with abnormal masticatory function.