Internet Archaeol. 16. Whitley. Non-causal references

3.3 Non-causal references

A third category of spatial proxy includes those which are not causally related to the cognitive behaviour under observation (Figure 3c). In these cases, the direct or indirect referential variables are no longer measurable and some alternatives must be identified which produce the same or similar relationships without being causally related themselves. This, of course, requires that they share a common causal factor with immeasurable variables, yet the cognitive behaviour and the currently measurable variable may be effects of a common cause, not influencing each other. A simple example is to use a visibility analysis as a proxy for sound or smell (e.g. Tschan et al. 2000, 44-47). Neither sound nor smell is directly or indirectly causally related to visibility (they are all truly independent), yet they are directly causally related to distance from the observer, as is visibility. Both sound and smell may be very influential in cognitive decision-making, and their causal relationships with a common variable, also causally related to visibility, suggests that one may, in some cases, act as a decent proxy for the others.