Abstract
Many classes of visual stimuli have a canonical orientation. Faces, animals, buildings, and other objects tend to appear at particular orientations, and behavioral studies show that we are sensitive to these canonical orientations. For example, when perceiving faces, we perform much better when faces are upright as opposed to rotated by 180° or even 90°. In recent work, we have shown that our visual system is sensitive not only to the internal (or egocentric) orientation of some visual stimuli, but also to their external (or environmental) orientation. We showed this in the perception of faces (Davidenko & Flusberg, 2012) and in the encoding of novel shapes (Davidenko & Flusberg, 2013). Here we investigate the perception of analog clocks, another class of stimulus with a canonical upright orientation. In Experiment 1 we show that sitting participants indeed take longer to correctly tell time on rotated clocks as a monotonic function of the angular deviation from upright. In Experiment 2, we manipulated both the participants' position (0°–sitting up, +90°–lying right, and -90°–lying left) and the clocks' orientation (from -180° to +135°, in 45° increments) and measured response times to correctly tell time on the clocks. We found that both egocentric and environmental orientation influenced response times. By fitting a sinusoidal curve through the median response times, we estimated the "optimal" angle for perceiving clocks for each observer position. When subjects lay sideways, the optimal angle was approximately 30° away from egocentric upright (toward environmental upright). This finding extends our previous results and suggests that environmental orientation influences performance in a variety of visual tasks, indicating an important role for environmental orientation in visual encoding. Furthermore, our results inform the design of visual displays that will be viewed from non-canonical positions.
Meeting abstract presented at VSS 2014