Michael L. Matthews

Discrimination of Identikit constructions of faces: Evidence for a dual processing strategy

Feature saliency and processing strategy in the recognition of faces are investigated in a “same”-“different” RT paradigm using pairs of faces constructed from Identikit representations. Facial sinailarity is varied by manipulating individual feature changes in pairs of faces. Although there was a general tendency for RT to increase as a function of facial similarity, analysis of RTs to component feature changes suggests a dual processing strategy whereby subjects give processing priority to hairline, eyes and chin, followed by a slower feature-by-feature analysis of eyebrows, nose, and mouth.

Visual performance and subjective discomfort in prolonged viewing of chromatic displays

Visual search and decision-making performance together with subjective fatigue were investigated over a 4-hr time block as a function of display foreground and background chromaticity using colors matched for brightness. Although some small differences in performance related to chromaticity were observed, these were not exacerbated over time. On the basis of the performance data obtained and the subjective reports, there was no support for the general recommendation to avoid the use of red and blue stimuli, either alone or in combination, in CRT displays.

The influence of visual workload history on visual performance

Two experiments are reported that demonstrate that visual search for a signal from a number of potential signal sources in a sustained monitoring task is dependent upon previous visual-load history. It is shown that both temporal and spatial variations in load produce performance decrements, and occasionally increments, that cannot be predicted from static-load experiments. These data are not consistent with previous attempts to explain performance changes associated with workload history. An interpretation is offered in terms of the persistence of information-processing strategies across changing task conditions.

Testing assumptions implicit in the use of the 15-second rule as an early predictor of whether an in-vehicle device produces unacceptable levels of distraction

Given the proliferation of in-vehicle technologies, techniques must be developed to ensure devices do not produce unacceptable levels of distraction. One approach is to use static time on task (e.g., the 15-second rule). However, this practice makes three critical assumptions: (1) static time on task predicts time on task while driving; (2) time on task measured in a hazard-free environment predicts time on task when drivers expect hazards; (3) time on task predicts perceived distraction, collisions, and driving errors. To test these assumptions, two tasks were compared in 32 drivers using a driving simulator. The tasks were manipulating controls of a radio/tape deck and dialling a hand-held cellular phone. Static time on task underestimated dynamic time on task, though the differences between tasks were roughly consistent across testing conditions, with the cellular task taking more time. Participants who expected hazards required slightly more time on task than those who did not, but the effect was only marginal (p=0.09) and consistent across tasks. Finally, the device with higher static time on task also produced significantly more lane deviations and perceived interference, though the predicted pattern of results did not emerge for collisions and hazard response time.

THE INFLUENCE OF VEHICLE TYPE ON THE ESTIMATION OF VELOCITY WHILE DRIVING

Velocity production in the absence of speedometer information was investigated as a function of car size. In the first experiment three vehicles of different sizes were driven by 30 subjects; in the second experiment a different sample of 20 subjects used their own vehicles, which were classified into two size categories. In both experiments subjects were required to drive under conditions of normal and attenuated auditory feedback. The results indicated a greater production accuracy in small compared with large cars and a tendency for drivers of small cars to make greater use of auditory information. The results are discussed in the context of the relative contribution of different sensory channels to the subjective scale of speed.

A Field Study of the Effects of Drivers' Adaptation to Automobile Velocity

A roadside survey of vehicle velocities was carried out by radar on a four lane, median divided highway with a 50 mile-per-hour (80 km/h) legal speed limit. Northbound traffic on the highway had been previously exposed to expressway conditions with vehicle speeds in excess of 96 km/h, whereas southbound traffic had been previously exposed to an urban highway with speeds of about 64 km/h. Northbound traffic velocities exceeded those of southbound traffic by an average of 6.9 km/h, which, it is argued, is the result of drivers of northbound vehicles being exposed to conditions under which velocity adaptation occurs. An analysis of the data by vehicle category indicates that while large cars are driven significantly faster than small cars under all conditions, the magnitude of the velocity adaptation effect is greater for drivers of small cars.

AGING AND THE PERCEPTION OF DRIVING RISK AND ABILITY

The purpose of this study was to determine how the perceived risk in certain driving situations and the perceived competence to handle such situations varies with age. Subjects in 3 age categories (18–25), (35–50), (65–75) made risk estimates for themselves and their peers for a variety of driving situations presented on videotape. In addition, they estimated confidence in their ability to handle such situations. In general, it was found that both younger and older drivers tended to underestimate the risk and overestimate their ability to handle the risk when compared with the intermediate age group. The implications of the findings are discussed in terms of risk taking behavior on the roads.

Critical Flicker Frequency in a Harp Seal: Evidence for Duplex Retinal Organization

Abstract Critical flicker frequency (CFF) was investigated in a free swimming harp seal using behavioral techniques. The resulting CFF vs intensity curve indicates a definite rod/cone break, suggesting a duplex photoreceptor population, whose presence had not been observed in previous morphological reports.

Spatial and temporal factors in masking by edges and disks

Increment threshold of a small test probe is found to be elevated by backgrounds of a disk, bar, or luminance step. The spatial parameters that produce maximum masking are found to be essentially similar with the three types of background. The lime course of masking is also found to be similar for the disk and bar background. It is suggested that a fundamentally similar type of visual processing underlies each of the masking situations.

The Influence of Color on Visual Search and Subjective Discomfort Using CRT Displays

Visual search and decision making performance together with subjective fatigue were investigated over a four hour time block as a function of display foreground and background chromaticity, using colors matched for equivalent brightness. Although some small differences in performance related to chromaticity were observed, these were not exacerbated over time. On the basis of the performance data obtained and the subjective reports, there would appear to be no support obtained for the general recommendation to avoid the use of red and blue stimuli either alone or in combination in CRT displays.