SPATIAL REPRESENTATION

NORMAL DEVELOPMENT, ADULT REPRESENTATION, AND SPECIAL EVIDENCE FROM WILLIAMS SYNDROME

Studies of spatial representation form a major part of our on-going research. But what do we mean by spatial representation? Abundant research in the cognitive, neuroscientific, and developmental literature attest to the idea that spatial representation is not a single omnibus system with a single set of characteristics. Rather, different kinds of spatial representation are highly specialized, both in terms of the function they serve, the computational properties they exhibit, and the brain mechanisms which subserve them (see Landau, 2003, for review). We are interested in a wide range of spatial capacities, including object representation, spatial navigation, spatial language, motion perception, visual-manual action in space, and imagery. Our research seeks to discover the cognitive characteristics of spatial representations, and to understand how these different kinds of representation "interface" with each other, to yield our seamless experience of a unitary spatial world. Although our work is designed to understand how spatial systems normally function, and how they develop under normal circumstances, we also study unusual populations that help us gain insight into the cognitive architecture of space. At present, we are studying individuals with Williams syndrome, a genetic condition that gives rise to extensive impairment to certain spatial systems.

 

A. Spatial Representation in Williams Syndrome and Normally Developing Children

 

Williams Syndrome (WS) is a rare genetic defect which results in a highly unusual cognitive profile of great interest to cognitive scientists and neuroscientists: People with WS exhibit profound spatial impairment, but relatively preserved language. For example, the pattern you see displayed above on the left is a simple combination of four individual blocks. Normal children can take such blocks and assemble the design shown above. Individuals with Williams Syndrome-- even as adults-- have great difficulty assembling such puzzles, showing impairment in an apparently simple task that taps basic spatial capacities. Similarly, people with WS have difficulty in visual-spatial construction tasks such as copying simple figures. The figure on the right shows two models (top row) and their copies by an adolescent with Williams syndrome. The severely impaired spatial skills, in combination with unusually strong language capacities adds up to a highly unusual profile of deficit and strength across different knowledge domains. This combination suggests the possibility that different cognitive domains may emerge in development along independent paths. These domains may also reflect differentiation in the development of brain systems that emerge early in life; and Williams syndrome may reflect a kind of specialized deficit in one or more of those systems.

We are engaged in a comprehensive program of research designed to determine the source and nature of the spatial deficit in children with Williams Syndrome, and its relationship to the development of spatial language. The work is collaborative with many individuals (see publication list), and involves many individuals in our lab, whose work examines different facts of the spatial deficit and/or spatial language. Current work examines:

Object recognition and identification (Landau, Hoffman, & Kurz, 2004; Hoffman & Landau, 2000a, 2000b)

Biological motion and perception of other kinds of motion (Jordan, Reiss, Hoffman, & Landau, 2002; Reiss, Hoffman, & Landau, 2003, 2004)

Object and spatial working memory (O'Hearn, Landau, Courtney, in progress)

Spatial language (object parts, events, spatial relationships among objects) (Landau & Zukowski, 2003; Lakusta & Landau, 2004; Landau & Hoffman, 2004)

Vision for action, vision for perception (Dilks, Landau, & Hoffman, 2001; Dilks, Landau, & Hoffman, 2003)

Spatial construction (Hoffman, Landau, & Pagani, 2003)

Visual-spatial integration (Palomares, Landau, Hoffman & Egeth, 2003; Ogbonna, Palomares, Landau, Hoffman, & Egeth, 2004)

Drawing and copying (Georgopoulos, Georgopoulos, Landau, & Kurz, 2004)

Multiple object tracking (O'Hearn, Landau, & Hoffman, 2004)

 

B. Navigation in normal adults: Interactions among the dead-reckoning system, imagery, and language.

Uyen Le and I have been examining the nature of interactions between the dead-reckoning system that all animals use for navigation, and higher-level cognitive systems such as imagery and language that are exclusively the province of humans. Le has found that real movement in space can serve to update imaginal representations of space, just as it can update representations of space that have been constructed from immediate perception of a layout. She is currently examining whether the powerful role of updating through real movement can also be applied to representations of layouts that are constructed through language. Please see Le and Landau (2004) for more information.