Influence of referential coding in a choice task performed in a simulated driving cockpit

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Xiong, Aiping
Cognitive Psychology; Industrial Engineering
thesis / dissertation description
Driving and other tasks performed by the driver of a vehicle are spatial. Thus, it is important to understand how the driver represents the spatial environment. In laboratory studies, the Simon task is used to study spatial coding. Participants are to make a left or right response to a nonspatial stimulus feature, but the stimulus can occur in a left or right position. The Simon effect is that responses are faster when the stimulus location corresponds with the response location. That effect is not usually found for a go/no-go task in which only one response is made to one of the relevant stimulus values, but it is when another person or referent object is placed beside the performer. This thesis tested whether an "infotainment display" in a driving cockpit produces a similar referential coding effect when responses are presses of a left or right button on the steering wheel. ^ Experiment 1 showed that the Simon effect was obtained for the left button but not the right button with a natural hand position, when a simulated infotainment display was located on the right of the steering wheel, simulating a right-hand vehicle cockpit. In Experiment 2, participants performed the same task, but with the display position on the left of the steering wheel, simulating a left-hand vehicle cockpit. The Simon effect in Experiment 2 tended to be smaller for left-hand responses than right-hand responses, but it was significant for both. Across the two experiments, though, spatial correspondence interacted with response (left hand; right hand) and display position (Experiment 1: right; Experiment 2: left): The Simon effect was significantly smaller for the response that was to the side of the infotainment display than for the response that was to the opposite side. ^ Because both responses tended to show positive Simon effects even when they were to the same side as the infotainment display, the display was removed in Experiment 3. In this case, both left- and right-hand responses showed Simon effects. This result, which differs from most prior studies of go/no-go Simon tasks, is likely a consequence of the non-responding hand being placed on the button used by that hand in the other test block. A Simon effect distribution analysis showed an increasing trend for the left-hand response but a stable trend for the right-hand response, regardless of display position. Although the Simon effect asymmetry relative to the infotainment display implicates coding with reference to that display, other factors such as differences between the left and right hands and participants' past experiences may also influence the results. ^ The results confirmed the spatial coding account of the Simon effect in an individual go-no/go Simon task paradigm. They also provide evidence as to how people code responses made with steering wheel buttons in a driving cockpit. The finding that the fastest responses were observed for the left button on the steering wheel for a right-hand vehicle implies that driving-related features should be placed on the left side.