Abstract
In a number of models of depth cue combination the depth percept is constructed via a weighted average combination of independent depth estimations. The influence of each cue in such average depends on the reliability of the source of information. (Young, Landy, & Maloney, 1993; Ernst & Banks, 2002.) In particular, Ernst & Banks (2002) formulate the combination performed by the human brain as that of the minimum variance unbiased estimator that can be constructed from the available cues.
Using slant discrimination and slant judgment via probe adjustment as tasks, we have observed systematic differences in performance of human observers when a number of different types of textures were used as cue to slant (Rosas, Wichmann & Wagemans, 2003). If the depth percept behaves as described above, our measurements of the slopes of the psychometric functions provide the predicted weights for the texture cue for the ranked texture types. We have combined these texture types with object motion but the obtained results are difficult to reconcile with the unbiased minimum variance estimator model (Rosas & Wagemans, 2003). This apparent failure of such model might be explained by the existence of a coupling of texture and motion, violating the assumption of independence of cues. Hillis, Ernst, Banks, & Landy (2002) have shown that while for between-modality combination the human visual system has access to the single-cue information, for within-modality combination (visual cues: disparity and texture) the single-cue information is lost, suggesting a coupling between these cues. Then, in the present study we combine the different texture types with haptic information in a slant discrimination task, to test whether in the between-modality condition the texture cue and the haptic cue to slant are combined as predicted by an unbiased, minimum variance estimator model.
YoungM.J.LandyM.S.MaloneyL.T.(1993). A perturbation analysis of depth perception from combinations of texture and motion cues. Vision Research, 33, 2685–2696.
ErnstM.O.BanksM.S.(2002). Humans integrate visual and haptic information in a statistically optimal fashion. Nature, 415, 429–433.
HillisJ.M.ErnstM.O.BanksM.S.LandyM.S.(2002). Combining sensory information: Mandatory fusion within, but not between, senses. Science, 298, 1627–1630.
RosasP.WichmannF.A.WagemansJ.(2003). Some observations on the effects of slant and texture type on slant-from-texture. Submitted.
RosasP.WagemansJ.(2003). Combination of texture and object motion in slant discrimination [Abstract]. Journal of Vision, in press.