The effects of healthy aging on mental imagery as revealed by egocentric and allocentric mental spatial transformations Luca De Simone a , Barbara Tomasino b , Nela Marusic a , Roberto Eleopra c , Raffaella Ida Rumiati a, ⁎ a Cognitive Neuroscience Sector, SISSA, Trieste, Italy b IRCCS “E. Medea”, San Vito al Tagliamento (PN), Italy c S.O.C. Neurologia, Azienda Ospedaliero Universitaria “Santa Maria della Misericordia”, Udine, Italy abstract article info Article history: Received 4 June 2012 Received in revised form 10 February 2013 Accepted 25 February 2013 Available online xxxx PsycINFO classification: 2300 Human Experimental Psychology 2340 Cognitive Processes Keywords: Aging Imagery Sensory Motor Laterality Previous studies suggest that mental rotation can be accomplished by using different mental spatial transforma- tions. When adopting the allocentric transformation, individuals imagine the stimulus rotation referring to its in- trinsic coordinate frame, while when adopting the egocentric transformation they rely on multisensory and sensory-motor mechanisms. However, how these mental transformations evolve during healthy aging has re- ceived little attention. Here we investigated how visual, multisensory, and sensory-motor components of mental imagery change with normal aging. Fifteen elderly and 15 young participants were asked to perform two differ- ent laterality tasks within either an allocentric or an egocentric frame of reference. Participants had to judge either the handedness of a visual hand (egocentric task) or the location of a marker placed on the left or right side of the same visual hand (allocentric task). Both left and right hands were presented at various angular departures to the left, the right, or to the center of the screen. When performing the egocentric task, elderly par- ticipants were less accurate and slower for biomechanically awkward hand postures (i.e., lateral hand orienta- tions). Their performance also decreased when stimuli were presented laterally. The findings revealed that healthy aging is associated with a specific degradation of sensory-motor mechanisms necessary to accomplish complex effector-centered mental transformations. Moreover, failure to find a difference in judging left or right hand laterality suggests that aging does not necessarily impair non-dominant hand sensory-motor programs. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Mental imagery (MI) is the distinctive human ability to create and transform mental representations of self and external objects. The debate on the underlying cognitive mechanisms of MI has emphasized the rele- vance of different classes of mental transformations (see Zacks & Michelon, 2005). A mental image can be mentally transformed, for in- stance, in order to process its visual features without the need for the ob- server to physically move the object or himself. In this case, an allocentric transformation, based on the updating of the object's intrinsic coordinate frame, is applied. It is also possible to use MI in order to transform our whole body image rotating or translating in the space. This latter process constitutes a form of egocentric transformation that involves the updating of the observer's reference frame (i.e., eye and head centered) like, for instance, during perspective taking tasks. When MI is applied to a specific body part, an effector-based transformation based on the effector reference frame (e.g., hand centered) is applied. This different form of egocentric transformation updates the coordinate frame of a specific body part relative to an object, to another body part or to the environment frame of reference making use of sensory-motor brain mechanisms that occur also during action planning and rehearsal (e.g., Michelon, Vettel, & Zacks, 2006; Parsons et al., 1995). One very fruitful way of studying MI has been trough mental rotation (MR) paradigms. MR has been first systematically explored by Shepard and Metzler (1971) in a series of experiments in which they visually presented participants with identical or mirror-image pairs of solid ob- jects and recorded reaction times (RTs) for same-different judgments. They found that participants' RTs monotonically increased with the in- crease of angular disparity between the two objects and argued that, in order to decide whether they are the same or different, participants mentally rotated one of the objects until it matched the position of the other. Similar results have been documented using laterality judgment about mirror-symmetric visual stimuli. For example in the “hand laterality task” observers were shown with a rotated picture of a hand and were asked to decide if the stimulus represents a left hand or a right hand. To perform this task it typically takes longer for larger hand rotations (Sekiyama, 1982; Parsons, 1987). However, it has also been shown that, differently from MR of solid abstract objects, MR of hands is strongly influenced by body part's somatic and kinesthetic aspects (Sekiyama, 1982; Parsons, 1987, 1994). Indeed, the hand laterality Acta Psychologica 143 (2013) 146–156 ⁎ Corresponding author at: Cognitive Neuroscience Sector, SISSA, Via Bonomea 265, 34136 Trieste, Italy. Tel.: +39 040 3787607; fax: +39 040 3787615. E-mail address: rumiati@sissa.it (R.I. Rumiati). 0001-6918/$ – see front matter © 2013 Elsevier B.V. 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