This article studies spatial relational inference within the framework of mental model theory. It focuses on the phase of model construction for which two cognitive modelings currently exist (Berendt, 1996; Schlieder, 1995). Both refer to the aggregated results of a former experiment (Knauff, Rauh & Schlieder, 1995). However, conflicting evidence exists with respect to symmetry properties of model construction that makes the assessment of the cognitive adequacy of certain explanations impossible. We therefore conducted an experiment using computational tools provided by AI research on Qualitative Spatial Reasoning (QSR) to investigate whether the model construction process works the same from left to right and vice versa (symmetry of reorientation), and whether the processing of spatial relations depends on what was already processed (symmetry of transposition). Experimental results clearly indicate that the symmetry of transposition cannot be found in subjects' answers to indeterminate spatial four-term series problems and that the degree of reorientation symmetry is not perfect. The latter, however, can be entirely attributed to performance variation, since the responses of retested subjects to the same problems were only concordant to the same degree.

An experiment based on Allen's calculus and its transfer to qualitative spatial reasoning, was conducted. Subjects had to find a conclusion X rj Z that was consistent with the given premises X rj Y and Yr2 Z. Implications of the obtained results are discussed with respect to the mental model theory of spa?tial inference. The results support the assumption that there are preferred models when people solve spatial three-term series problems. Although the subjects performed the task surpris?ingly well overall, there were significant differences in error rates between some of the tasks. They are discussed with respect to the subprocesses of model construction, model inspection, validation of the answer, and the interaction of these subprocesses.

Two experiments on spatial relational inference investigated effects known from relational and syllogistic reasoning. (1) Continuity effect; n-term-series problems with continuous (W r1 X, X r2 Y, Y r3 Z) and semi-continuous (X r2 Y, Y r3 Z, W r1 X) premise order are easier than tasks with discontinuous order (Y r3 Z, W r1 X, X r2 Y). (2) Figurai bias: the order of terms in the premises (X r Y. Y r Z or Y r X, Z r Y) effects the order of terms in the conclusion (X r Z or Z r X). In the first experiment subjects made more errors and took more time to process the premises when in discontinuous order. In the second experiment subjects showed the general preference for the term order Z r X in the generated conclusions, modulated by a "figural bias": subjects used X r Z more often if the premise term order was X r Y , Y r Z, whereas Z r X was used most often for the premise term order Y r X, Z r Y. Results are discussed in the framework of mental model theory with special reference to computational models of spatial relational inference.