Observer pitch and roll influence: the rod and frame illusion.
Observers misperceive the orientation of a vertical rod when it is viewed in the context of a tilted frame (the rod and frame illusion, or RFI). The pitch and roll of the surrounding surfaces have independent influences on this illusion (Nelson and Prinzmetal, 2003). Experiment 1 measured the RFI when the pitch and roll of the floor that supported the observer was varied, and the observer was either seated in a chair or standing upright. There were additive influences of pitch and roll on the RFI of seated but not standing observers. Experiments 2 and 3 decoupled body roll and head roll in order to isolate the vestibular and proprioceptive contributions to these effects. The results are interpreted in support of a hierarchy of influence on the RFI: Visual input is given top priority, followed by vestibular input, and then proprioceptive input.
Corbett
Jennifer E
JE
Department of Psychology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. jecorbet@psych.ubc.ca
Enns
James T
JT
D000293:Adolescent; D000328:Adult; D004193:Discrimination Learning; D005260:Female; D005364:Field Dependence-Independence; D006801:Humans; D007699:Kinesthesis; D008297:Male; D009903:Optical Illusions; D009949:Orientation; D010364:Pattern Recognition, Visual; D004856:Postural Balance; D011434:Proprioception; D011601:Psychophysics