1. Fion C.H. Lee, Alan H.S. Chan International Journal of Industrial Ergonomics 37 (2007) 197–206 Attending visual and auditory signals: Ergonomics recommendations with consideration of signal modality and spatial stimulus–response (S–R) compatibility 學生. 莊靖玟

2. Introduction As a result of advancing technology and the consequent complexity of machines used in industry, operators need to attend to different modality signals transmitted from different machinery and equipment in their daily tasks.

3. Introduction Visual and auditory signals are the two most commonly used modalities for getting attention and soliciting responses from the operators.

4. Reference Auditory signals are obviously more effective when sources are beyond the visual field of view, and can be used to reduce high visual workload in complex systems (Bronkhorst et al., 1996; Nanthavanij and Yenradee, 1999).

5. Reference Simple visual reaction time was generally longer than the simple auditory reaction time when the two modalities were presented and responded to separately. The generally accepted mean was 140 ms for auditory signals and 180ms for visual signals. (Brebner and Welford, 1980).

6. Reference Visual signals have also shown to have a tendency to dominate awareness of other sensory inputs, including proprioceptive and tactile ones. (Posner et al., 1976).

7. Reference Shorter reaction times were obtained when there was a correspondence between the spatial position of a display and the position of the control response, than when there was no correspondence (Ghozlan, 1997;Roswarski and Proctor, 2000; Chan and Chan, 2005).

8. Reference Fundamental knowledge of sound properties tells us that auditory S–R compatibility may be restricted in some ways due to the difficulty of perceiving positional differences of auditory signals straight ahead or behind, as there are no differences in intensity or phase of the sounds to be detected. (Alten, 1996).

9. Purpose The authors to conduct the present study to further investigate the effect of visual signal strength on performance with auditory and visual signals.

10. Method - Subjects Thirty-two undergraduates of City University of Hong Kong (16 males and 16 females) The ages of 21–24 Right-handed All of them had normal or corrected-to- normal vision No hearing loss

11. Method ＊ A personal computer ＊ A Philips stereo headphone (SBS HP140) ＊ A 15” color CRT Monitor 80mm 直徑 20mm 500mm Four response keys A tone of 55 dBA was presented to either ear through a headphone.

12. Method BCAC VCBI

13. Method Each subject performed all the four S–R mapping conditions. The testing order of the four conditions was counterbalanced across the subjects. There were eight practice trials and 20 trials in each mapping condition. Within a trial, either one of the visual or auditory signals would appear.

14. Method 1~4s signal 900ms or until a response

15. Method The time elapsed from the signal onset to the successful detection of key response by the computer was taken as the reaction time. No feedback on the accuracy of their responses in testing trials was given to the subjects. There was a short break after testing each of the mapping conditions.

16. Results - Reaction time A total of 2560 responses (32 subjects×4 spatial mapping conditions×20 trials) were collected in the experiment. There were 43 (1.68%) incorrect responses. Altogether 50 responses (1.95%) were discarded. A total of 2467 responses (96.37%) were left for further analysis. Subjects’ gender effect was found to be non-significant on mean reaction time [F(1, 30) = 1.189, p>.05].

17. Results

20. Visual signals were found to yield faster responses (735 ms) than auditory signals (754 ms), though the factor was not significant [F(1, 31) ＝ 1.21, p>.05]

21. Results

26. Results - Response error Out of the total of 2560 responses collected from the subjects, 43 (1.68%) were incorrect. No significant effect was found between males and females on mean error percentage (p>.05). The effects of AVSR compatibility and warning time on EPs results showed that both factors were not significant (p>.05).

27. Results

29. Response speed was determined by the spatial S–R compatibility effect and signal modality effect. Response accuracy was determined by the signal modality factor.

30. Discussion There were three main findings. First, a strong spatial S–R compatibility effect was observed for both signal modalities and such correspondence of S– R positions elicited relatively faster responses. However, in a condition when either the visual or the auditory pairing was incompatible, reaction times increased dramatically.

31. Discussion Second, responses made to the visual signals were generally faster than those to the auditory signals. This contradicted the previous finding that simple visual reaction time was longer than simple auditory reaction time.

32. Discussion Third, a superior visual strength effect was observed in this choice reaction task. This visual strength effect was more marked in the conditions with conflicting S–R mapping pairings.