35 subjects, randomly assigned to five groups in a 2 x 2 + 1 between-subjects design, performed a vigilance task under familiar rock, familiar easy-listening, unfamiliar rock, unfamiliar easy-listening, and no music conditions. Familiar music significantly increased heart rate and percent detections and also mitigated the classical vigilance decrement. Type of music had no significant effect. It was concluded that the psychological chaaracteristics of noise are at least as important as its physical characteristics in determining level of vigilance performance.

The Hebrew Academy of Language in Israel has ruled that numerical ranges shall be written from right-to-left (lower number on right, higher number on left), consistent with language direction. This pilot study investigated the effect of that rule on human performance in a simulated directional sign-reading task. Right-to-left text, followed by single digit number sets depicting a range of values were presented to sixteen native Hebrew speakers, who were asked to report whether an additional number presented separately appeared within that range. Number sets following the Hebrew text were presented from left-to-right and from right-to-left. No significant differences were found in response times between left-to-right and right-to-left conditions. However, a significant main effect of direction was found for percent errors, which were significantly higher for right-to-left than for left-to-right number sets. The rule requiring number sets to appear from right-to-left is called into question, and implications for numerical range information display in right-to-left languages are suggested. The authors are currently engaged in more extensive research aimed at expanding the findings of this pilot study.

This tidy addresses the question of whether there is value to the use of animation in icon design over and above that of r&acting aaention Specifically, the stody asks if there is any basis in human performawe for recommending for or against the we of animation in icon design. The objective was to examine the effect of animation on icon comprehension and preference at two levels of complexity, as measured in the context of a supermarket-shopping computer program. Results suggest that animation can contribute to users' comprehension of icons that represent commaads, and that this contribution may be greater for commands of higher levels of abstraction. Specifically, it appears that simple icons are more comprehensible than complex ones for commands of lower levels of abstraction, while complex icons are more comprehensible than simple ones for commands of higher levels of abstraction. Moreover, animation of complex icons that represent abstract commands may improve icon comprehension far more than animation of either simple or complex icons that represent less abstract commaads. The notion that animation can be used intelligently to improve human performance ia HCI is supported. Further research is encouraged to identify ways in which levels of command abstraction can be measured reliably, aad to establish guidelines for the level of abstraction at which complexity and animation should be introduced into icon design.

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