title: How coordinate and categorical spatial relations combine with egocentric and allocentric reference frames in a motor task: effects of delay and stimuli characteristics.
abstract: This study explores how people represent spatial information in order to accomplish a visuo-motor task. To this aim we combined two fundamental components of the human visuo-spatial system: egocentric and allocentric frames of reference and coordinate and categorical spatial relations. Specifically, participants learned the position of three objects and then had to judge the distance (coordinate information) and the relation (categorical information) of a target object with respect to themselves (egocentric frame) or with respect to another object (allocentric frame). They gave spatial judgments by reaching and touching the exact position or the side previously occupied by the target object. The possible influence of stimuli characteristics (3D objects vs. 2D images) and delay between learning phase and testing phase (1.5 vs. 5s) was also assessed. Results showed an advantage of egocentric coordinate judgments over the allocentric coordinate ones independently from the kind of stimuli used and the temporal parameters of the response, whereas egocentric categorical judgments were more accurate than allocentric categorical ones only with 3D stimuli and when an immediate response was requested. This pattern of data is discussed in the light of the "perception-action" model by Milner and Goodale [13] and of neuroimaging evidence about frames of reference and spatial relations.
authors.affiliation: Department of Experimental Psychology, University of Utrecht, The Netherlands; Laboratory of Cognitive Science and Immersive Virtual Reality, Second University of Naples, Italy. Electronic address: f.ruotolo@uu.nl.
authors.forename: Francesco
authors.initials: F
authors.lastname: Ruotolo
authors.affiliation: Department of Experimental Psychology, University of Utrecht, The Netherlands.
authors.forename: Ineke
authors.initials: I
authors.lastname: van der Ham
authors.affiliation: Department of Experimental Psychology, University of Utrecht, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: Postma
authors.affiliation: Laboratory of Cognitive Science and Immersive Virtual Reality, Second University of Naples, Italy.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Ruggiero
authors.affiliation: Laboratory of Cognitive Science and Immersive Virtual Reality, Second University of Naples, Italy.
authors.forename: Tina
authors.initials: T
authors.lastname: Iachini
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007600:Judgment; D007858:Learning; D008297:Male; D010812:Physical Stimulation; D011597:Psychomotor Performance; D011897:Random Allocation; D011930:Reaction Time; D012649:Self Concept; D013028:Space Perception; D055815:Young Adult
keywords: Delay; Motor task; Reference frame; Spatial relation; Stimuli manipulability