Inter-process relations in spatial language: Feedback and graded compatibility.

Mapping spatial expressions such as "behind the cup" to a spatial region requires two processes that have been largely explored independently: reference frame selection and spatial term assignment (Logan & Sadler, 1996). Reference frame selection carves a space into regions. Spatial term assignment evaluates these regions by determining the acceptability of the term for the given configuration. Here we present a systematic investigation of the relation and interplay of these two processes by asking whether (a) information from spatial term assignment feeds back to selection and (b) whether competition during selection is graded. In a series of simulation studies, we assess the performance of four computational models, each of which instantiates a unique combination of feedback (no feedback vs. feedback) and gradedness (all-or-none compatibility vs. graded compatibility). The results support two key observations about human spatial term use: First, reference frame selection and spatial term assignment proceed concurrently and in mutual interaction, with assignment information feeding back and influencing the selection process. Second, competition in reference frame selection is graded such that the strength of competition between different available reference frames increases continuously with decreasing similarity of the frames. As such, our work provides a new view on the components involved in spatial term use and their interplay, and suggests more broadly that the gradedness of competition may also be an important aspect of conflict and selection in other cognitive domains.