Why do Alzheimer patients have difficulty with pronouns? Working memory, semantics, and reference in comprehension and production in Alzheimer's disease

Three experiments investigated the extent to which semantic and working-memory deficits contribute to Alzheimer patients' impairments in producing and comprehending referring expressions. In Experiment 1, the spontaneous speech of 11 patients with Alzheimer's disease (AD) contained a greater ratio of pronouns to full noun phrases than did the spontaneous speech produced by 9 healthy controls. Experiments 2 and 3 used a cross-modal naming methodology to compare reference comprehension in another group of 10 patients and 10 age-matched controls. In Experiment 2, patients were less sensitive than healthy controls to the grammatical information necessary for processing pronouns. In Experiment 3, patients were better able to remember referent information in short paragraphs when reference was maintained with full noun phrases rather than pronouns, but healthy controls showed the reverse pattern. Performance in all three experiments was linked to working memory performance but not to word finding difficulty. We discuss these findings in terms of a theory of reference processing, the Informational Load Hypothesis, which views referential impairments in AD as the consequence of normal discourse processing in the context of a working memory impairment.     

Influence of sex and gender roles on high school status systems

Past research has indicated significant sex differences in determinants of male and female high school students' status as measured by how subjects would like to have been remembered from their high school years. In order to determine if remembrance preference is sex or gender role related, 671 subjects were administered the Bem Sex-Role Inventory (BSRI) and a questionnaire asking if they most wanted to be remembered from high school as a brilliant student, leader in activities, athletic star or most popular. Using both the median split and t-ratio procedures in scoring the BSRI, 206 subjects were selected because they were sex-typed (masculine males, feminine females), cross sex-typed (masculine females, feminine males), or androgynous (scoring high on both masculine and feminine traits). To find a model of best fit, the data were subjected to a log-linear analysis. The variables included were sex, gender role, and remembrance preference. Rather than sex being the influential factor, the model of best fit was a gender role by remembrance preference interaction. If subjects were masculine, they were more likely to choose athletic star than were feminine or androgynous subjects. Most popular and leader in activities were both more likely to be chosen by feminine and androgynous subjects. All groups chose brilliant student more often than any other category. It was concluded that some previously designated sex differences may instead be differences in gender role. Further research should address the distinction between the two.     

The ground dominance effect in the perception of relative distance in 3-D scenes is mainly due to characteristics of the ground surface

Previously, we (Bian, Braunstein, and& Andersen, 2005) reported a dominance effect of the ground plane over other environmental surfaces in determining the perceived relative distance of objects in 3-D scenes. In the present study, we conducted three experiments to investigate whether this ground dominance is due to inherent differences between ground and ceiling surfaces, or to the locations of these surfaces in the visual field. In Experiment 1, two vertical posts were positioned between a ground surface and a ceiling surface, and optical contact was manipulated so that the two surfaces provided contradictory information about the relative distances of the posts from the participant. The two surfaces were either both above, both below, or one above and one below fixation. In Experiment 2, only one surface was presented, either above, below, or at fixation. In Experiment 3, the posts were replaced by two red dots, and the eccentricity of the optical contact on the two surfaces was equated in each of five locations in the visual field. In all three experiments, participants judged which of the two objects appeared to be closer. Overall, we found a higher proportion of judgments consistent with a ground surface than with a ceiling surface in all locations, indicating that the ground dominance effect is mainly due to characteristics of the ground surface, with location in the visual field having only a minor effect.     

The ground dominance effect in the perception of 3-D layout

The relative effectiveness of the ground surface and other environmental surfaces (the ceiling and sidewalls) in determining perceived layout was investigated in five experiments and a real-world demonstration. In the first three experiments, two vertical or horizontal posts were positioned between two surfaces (ground and ceiling in all three experiments, left wall and right wall in Experiment 1), and optical contact was manipulated so that the two surfaces provided contradictory information about the relative distances of the posts. Observers judged which of the two posts appeared to be closer. In Experiment 4, to control the height on the posts at which the distance judgments were made, a blue dot was attached to both vertical posts at varying heights and observers judged which dot appeared closer. In Experiment 5, the posts were replaced by two gray ellipses to eliminate the effects of the regular shape and texture. Our findings were that (1) among all four surfaces tested, observers showed a preference to respond according to the optical contact information provided by the ground surface--a ground dominance effect, (2) this effect did not depend on the height of the posts in the image, (3) as the scene was tilted away from a ground/ceiling orientation, the ground dominance effect decreased, and (4) this effect was not due to the location of the judgment.     

Sentence Comprehension Deficits in Alzheimer''s Disease: A Comparison of Off-Line vs. On-Line Sentence Processing

Two studies explored whether sentence comprehension impairments in Alzheimer's disease (AD) are due to deficits in syntactic processing or memory. Study 1 used a picture-pointing sentence comprehension task to measure the final outcome of comprehension in an off-line fashion. It showed the comprehension of 30 patients with AD to be impaired, but suggested that the deficits could not be attributed solely to syntactic impairments. Study 2 investigated the effects of memory on sentence comprehension by comparing off-line (grammaticality judgment) with on-line (cross-modal naming) language processing in 11 AD and 9 control subjects. The results revealed impaired performance in the off-line task but normal performance in the on-line task using the same sentences. Performance on the off-line task correlated with independent measures of verbal working memory. These data are used to argue that sentence comprehension impairments are related to verbal working memory deficits in AD.     

Perception of three-dimensional structure from motion

The ability to perceive the 3-D shape of objects solely from motion cues is referred to as structure-from-motion perception. Recent experiments indicate how this remarkable perceptual attribute is computed by the brains of primates. This computation proceeds in at least two stages, one in which motion measurements are made and another in which moving surfaces are reconstructed. The middle temporal area (MT) in the macaque monkey appears to play a pivotal role in the latter step and suggests a previously unappreciated function for this well-known cortical region, which had previously been thought to play a more rudimentary role in simply signaling the direction of motion of images.     

"Do I know you?" The role of significant others in general social perception

This research used an idiographic method to examine the proposition that significant others are mentally represented as well-organized person categories that can influence social perception even more than representations of nonsignificant others, stereotypes, or traits. Together, Studies 1 and 2 showed that significant-other representations are richer, more distinctive, and more cognitively accessible than the other categories. Study 3 replicated the accessibility data and gauged inferential power by indirectly activating each category in a learning trial about a fictional person and then testing recognition memory. The results showed that participants made more category-consistent false-positive errors about targets who activated significant others vs. any other category. This constitutes the first experimental demonstration of transference and has implications both for social categorization and for basic personality processes.