Stable Self-to-Object Spatial Relations Acquired from Sequential Spatial Learning

Stable Self-to-Object Spatial Relations Acquired from Sequential Spatial Learning Chengli Xiao (xiaocl@nju.edu.cn) Department of Psychology, Nanjing University, 22 Hankou Road Nanjing 210093, P.R. China Fudan Chen (cfdchashao@163.com) Department of Psychology, Nanjing University, 22 Hankou Road Nanjing 210093, P.R. China Abstract Self-to-object spatial relations are generally considered to be transient and supported primarily by perceptual processes. The present study investigates whether people can acquire stable self-to-object spatial relations that are not disrupted by disorientation. Participants either simultaneously or sequentially viewed the object locations from a learning position amidst a geometrically irregular array. Next they were blindfolded and pointed to the objects under three conditions: before turning (baseline), after rotating 240° (updating), and after disorientation (disorientation). Finally, all participants were taken to another room to perform judgments of relative direction (JRDs) among remembered object locations. The internal consistency of pointing among objects was disrupted by disorientation following simultaneous viewing but not sequential viewing. However, participants’ memories of object-to-object relations were equivalent in the two viewing conditions. Together, these results suggest that people construct stable self-to-object spatial relations when they sequentially view each object of the irregular layout. Keywords: self-to-objection spatial relations; sequential learning; disorientation Introduction In everyday life, people use self-to-object (egocentric) and object-to-object (allocentric) spatial relations to encode the location of objects or landmarks in the environment, navigate effectively to significant places, and reorient themselves when getting lost. In a self-to-object reference system, locations are represented with respect to the particular perspective of a perceiver, whereas in an object- to-object reference system, locations are represented within a framework external to the holder of the representation and independent of his or her position e.g., Easton & Sholl, 1995; Klatzky, 1998). Generally, it is believed that self-to-object spatial relations are transient and supported primarily by the perceptual processes, and that object-to-object spatial relations are stable and can be preserved in the memory system (e.g., Burgess, 2006; Holmes & Sholl, 2005; Mou, McNamara, Valiquette, & Rump, 2004). When moving around the environment, if people navigate by means of the self-to-object spatial relations, one has to add a common vector to each individual target vector to compute the new egocentric coordinates of the target locations. If this updating process is disrupted through procedures that induce a state of disorientation, the coherence of relative locations among different targets is reduced. Therefore, a disoriented participant's pointing response will show an inconsistency among different targets (disorientation effect). To the contrary, if people navigate by means of the object-to-object spatial relations, which remains the same regardless of people’s movements, the state of disorientation cannot reduce the coherence of relative locations among different targets. Therefore, the consistency of the pointing response among different targets will be equal between oriented and disoriented participants (absence of disorientation effect). By measuring the standard deviation across target objects of the mean signed pointing errors (configuration error), the accuracy of the localization of each target in relation to the others can be assessed. Following this logic, recent research has indicated that people can navigate by means of either the transient self-to-object or stable object-to-object spatial representations (Holmes & Sholl, 2005; Mou, McNamara, Rump, & Xiao, 2006; Sargent, Dopkins, Philbeck, & Modarres, 2008; Waller & Hodgson, 2006; Wang & Spelke, 2000). In most situations, people acquire both self-to-object and object-to-object spatial representations, and can navigate by means of one of them according to the layout geometry or instruction (Xiao, Mou, & McNamara, 2009). However, in all the previous research, which indicated that people were able to navigate by means of transient self- to-object spatial representations, the pointing responses of disoriented participants still had a relatively high consistency among different targets. The configuration errors in the disorientation condition were no more than 30°, which were much less than the expected configuration error of randomly pointing (approaching 104°). It is possible that disorientation does not totally disrupt the self-to-object spatial representations, and that the disoriented participants can still locate objects based on the impaired self-to-object spatial representations that persist in their memory. One of our recent experiments provided circumstantial evidence for this hypothesis (Xiao, et al., 2009). After visually learning object locations amidst, or at the periphery of an irregular array (see Figure 1), blindfolded participants pointed to the objects before turning (baseline), after rotating 240° (updating), and after disorientation (disorientation). In both learning conditions, the configuration error significantly increased after disorientation, indicating that the participants located objects by means of the self-to-object spatial relations. When explicitly instructed to use the object-to-