Implications of differences of echoic and iconic memory for the design of multimodal displays
Glaser, Daniel Shields
Lane, David M.
Doctor of Philosophy
It has been well documented that dual-task performance is more accurate when each task is based on a different sensory modality. It is also well documented that the memory for each sense has unequal durations, particularly visual (iconic) and auditory (echoic) sensory memory. In this dissertation I address whether differences in sensory memory (e.g. iconic vs. echoic) duration have implications for the design of a multimodal display. Since echoic memory persists for seconds in contrast to iconic memory which persists only for milliseconds, one of my hypotheses was that in a visual-auditory dual task condition, performance will be better if the visual task is completed before the auditory task than vice versa. In Experiment 1 I investigated whether the ability to recall multi-modal stimuli is affected by recall order, with each mode being responded to separately. In Experiment 2, I investigated the effects of stimulus order and recall order on the ability to recall information from a multi-modal presentation. In Experiment 3 I investigated the effect of presentation order using a more realistic task. In Experiment 4 I investigated whether manipulating the presentation order of stimuli of different modalities improves humans' ability to combine the information from the two modalities in order to make decision based on pre-learned rules. As hypothesized, accuracy was greater when visual stimuli were responded to first and auditory stimuli second. Also as hypothesized, performance was improved by not presenting both sequences at the same time, limiting the perceptual load. Contrary to my expectations, overall performance was better when a visual sequence was presented before the audio sequence. Though presenting a visual sequence prior to an auditory sequence lengthens the visual retention interval, it also provides time for visual information to be recoded to a more robust form without disruption. Experiment 4 demonstrated that decision making requiring the integration of visual and auditory information is enhanced by reducing workload and promoting a strategic use of echoic memory. A framework for predicting Experiment 1-4 results is proposed and evaluated.