Laura Lakusta

Impaired geometric reorientation caused by genetic defect

The capacity to reorient in one’s environment is a fundamental part of the spatial cognitive systems of both humans and nonhuman species. Abundant literature has shown that human adults and toddlers, rats, chicks, and fish accomplish reorientation through the construction and use of geometric representations of surrounding layouts, including the lengths of surfaces and their intersection. Does the development of this reorientation system rely on specific genes and their action in brain development? We tested reorientation in individuals who have Williams syndrome (WS), a genetic disorder that results in abnormalities of hippocampal and parietal areas of the brain known to be involved in reorientation. We found that in a rectangular chamber devoid of surface feature information, WS individuals do not use the geometry of the chamber to reorient, failing to find a hidden object. The failure among people with WS cannot be explained by more general deficits in visual-spatial working memory, as the same individuals performed at ceiling in a similar task in which they were not disoriented. We also found that performance among people with WS improves in a rectangular chamber with one blue wall, suggesting that some individuals with WS can use the blue wall feature to locate the hidden object. These results show that the geometric system used for reorientation in humans can be selectively damaged by specific genetic and neural abnormalities in humans.

Spatial representation across species: geometry, language, and maps

We review growing evidence that the reorientation system-shared by both humans and nonhuman species-privileges geometric representations of space and exhibits many of the characteristic features of modular systems. We also review evidence showing that humans can move beyond the limits of nonhuman species by using two cultural constructions, language and explicit maps. We argue that, although both of these constructions are uniquely human means of enriching the spatial system we share with other species, their representational formats, functions, and developmental trajectories are quite different, yielding distinctly different tools for empowering human spatial cognition.The capacity to reorient using geometry is present in humans by the age of 18 months.

Language and Memory for Motion Events: Origins of the Asymmetry Between Source and Goal Paths

When people describe motion events, their path expressions are biased toward inclusion of goal paths (e.g., into the house) and omission of source paths (e.g., out of the house). In this paper, we explored whether this asymmetry has its origins in peoples non-linguistic representations of events. In three experiments, 4-year-old children and adults described or remembered manner of motion events that represented animate/intentional and physical events. The results suggest that the linguistic asymmetry between goals and sources is not fully rooted in non-linguistic event representations: linguistic descriptions showed the goal bias for both kinds of events, whereas non-linguistic memory for events showed the goal bias only for events involving animate, goal-directed motion. The findings are discussed in terms of the mapping between non-linguistic representations of goals and sources in language, focusing on the role that linguistic principles play in producing a more absolute goal bias from more gradient non-linguistic representations of paths.

The intention-to-CAUSE bias: Evidence from children’s causal language

The current study explored causal language in 3.5- to 4-year-old children by manipulating the type of agent (human acting intentionally or unintentionally, or inanimate object) and the type of effect (motion or state change) in causal events. Experiment 1 found that the type of agent, but not the type of effect, influenced childrens production of causal language. Children produced more causal language for intentionally caused events than for either unintentionally- or object-caused events, independent of the type of effect. Experiment 2, which tested childrens judgments of descriptions for the events, found a similar pattern. Children preferred causal descriptions more for the intentionally caused events than the unintentionally- and the object-caused events. Experiment 3 found no evidence of bias in childrens non-linguistic representations of the events. Taken together, these results suggest an intention-to-CAUSE bias in childrens mapping of conceptual representations of causality into linguistic structure. We discuss the implications of these results for the acquisition of causal language and for the development of conceptual representations of causality.

Deficits in adults with Autism Spectrum Disorders when processing multiple objects in dynamic scenes

People with autism spectrum disorders (ASD) process visual information in a manner that is distinct from typically developing individuals. They may be less sensitive to peoples goals and, more generally, focus on visual details instead of the entire scene. To examine these differences, people with and without ASD were asked to detect changes in dynamic scenes with multiple elements. Participants viewed a brief video of a person or an inanimate object (the “figure”) moving from one object to another; after a delay, they reported whether a second video was the same or different. Possible changes included the figure, the object the figure was moving from, or the object the figure was moving toward (the “goal”). We hypothesized that individuals with ASD would be less sensitive to changes in scenes with people, particularly elements that might be the persons goal. Alternately, people with ASD might attend to fewer elements regardless of whether the scene included a person. Our results indicate that, like controls, people with ASD noticed a change in the “goal” object at the end of a persons movement more often than the object at the start. However, the group with ASD did not undergo the developmental improvement that was evident typically when detecting changes in both the start and end objects. This atypical development led to deficits in adults with ASD that were not specific to scenes with people or to “goals.” Improvements in visual processing that underlie mature representation of scenes may not occur in ASD, suggesting that late developing brain processes are affected. Autism Res 2011, 4: 132–142.

Twelve-Month-Old Infants’ Encoding of Goal and Source Paths in Agentive and Non-Agentive Motion Events

Across languages and event types (i.e., agentive and nonagentive motion, transfer, change of state, attach/detach), goal paths are privileged over source paths in the linguistic encoding of events. Furthermore, some linguistic analyses suggest that goal paths are more central than source paths in the semantic and syntactic structure of motion verbs. However, in the nonlinguistic memory of children and adults, a goal bias shows up only for events involving intentional, goal-directed, action. Three experiments explored infants’ nonlinguistic representations of goals and sources in motion events. The findings revealed that 12-month-old infants privilege goals over sources only when the event involves action of an agent. Thus, unlike language (but similar to the memory of children and adults), an endpoint bias in infant thought may be restricted to events involving goal-directed motion by an agent. These results raise the question of how children later learn to collapse over conceptual domains for purposes of coding paths in language.