Viewer- and object-centered mental explorations of an imagined environment are not equivalent

In this study we compared viewer-centered (VC) with object-centered (OC) mental exploration of an imagined clock drawn on the ground. An upper case F portrayed on a computer screen was to be imagined standing up in the center of the clock. In Expt. 1, an adjustment task was used to verify that the discrimination of clock directions rendered by this perspective drawing was quite accurate. Precision was not affected by the imaginary size of the clock. In Expt. 2, subjects either (1) indicated the clock location pointed by the F given their viewing position (VC condition), or (2) their location at the periphery of the clock given the location pointed by the F (OC condition). Response latencies were proportional to the explored imaginary distance and increased with the size of the imagined environment. We found an additional mean processing time of at least 2 s in the OC condition with respect to the VC condition. Results are interpreted within Kosslyn's (Kosslyn, S.M., A cognitive neuroscience of visual cognition: further developments. In: R.H. Logie and M. Denis (Eds.), Mental Images in Human Cognition, Elsevier Science Publishers, Amsterdam, 1991, pp. 351-381 [17]) framework of cognitive neuroscience.