Amit Almor

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 Alzheimers 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.

Angiotensin Converting Enzyme Inhibitors and Cognitive and Functional Decline in Patients with Alzheimer's Disease: An Observational Study

We previously reported that angiotensin converting enzyme inhibitors (ACEIs) decrease the rate of cognitive decline in elderly patients with hypertension, but their impact on patients with Alzheimers disease (AD) is not known. A total of 62 elderly patients with AD were enrolled, and 52 completed the study for 6 months. Mini-Mental Status Examination (MMSE), Clock Draw Test (CDT), working memory (Digit Ordering), Instrumental Activities of Daily Living (IADL) scale, and the Screen for Caregiver Burden (SCB) were collected at baseline, 3 months, and 6 months. AD patients receiving ACEI (N = 15) demonstrated a slower rate of decline in digit forward (P = .003) and IADL scale (P = .003) and an improved measure of caregiver burden (P = .04) but not MMSE (P =.15) or CDT (P =.9) compared with those not receiving ACEI after adjusting for other risk factors. This study suggests that use of ACEI in AD patients is associated with slower rate of AD progression. A randomized clinical trial is needed to confirm our finding.

Information content versus relational knowledge: Semantic deficits in patients with Alzheimer's disease

Studies of semantic impairment in Alzheimers disease (AD) have yielded conflicting results, some finding evidence of considerable deficits, others finding that semantic knowledge is relatively intact. How do we reconcile findings from picture naming tasks that seem to indicate semantic impairment in AD with results from certain sorting tasks that suggest intact semantics? To investigate the basis of the contradictory results described above, we conducted a study using two types of tasks: (1) picture naming; and (2) board sorting. The board sorting task we used is a simultaneous similarity judgment task, in which participants are asked to place more similar concepts closer together and less similar ones farther apart. We compared the performance of AD patients on these two tasks, using a number of different analyses that yield very different patterns of results. Our results indicate that whether patients show impairment or not depends on both the nature of the task and the subsequent analysis chosen. Specifically, tasks and analyses that focus on relational knowledge (e.g., dog is more related to cat than to camel) lead to different conclusions than those based on specific information about individual items. These findings suggest that the board sorting method, when coupled with multiple analyses, provides a more complete picture of the underlying semantic deficit in AD than previous studies have shown.

Comprehension of long distance number agreement in probable Alzheimer's disease

Two cross-modal naming experiments examined the role of working memory in processing sentences and discourses of various lengths. In Experiment 1, 10 memory impaired patients with probable Alzheimers disease (AD) and 10 healthy elderly control participants showed similar sensitivity to violations of subject-verb number agreement in a short sentence condition and similar degradation to this sensitivity in a long sentence condition. Performance in neither length condition correlated with performance on working memory tasks, suggesting that the processes involved in interpreting a grammatical dependency between adjacent and nonadjacent elements are different from those required in the working memory tasks. In Experiment 2, the same 10 AD patients were less sensitive than the 10 control participants to pronounantecedent number agreement violations in a short discourse condition, but neither group was affected by additional length. In this experiment, performance in both the short and long conditions correlated with working memory performance. These results show that grammatical and discourse dependencies pose different memory and processing demands, and that these differences are not simply due to differences in the amount of intervening material between dependent words. The results also suggest that while the working memory deficits characteristic of AD do not interfere with on-line grammatical processing within sentences, they do compromise on-line discourse processing across sentences. Two cross-modal naming experiments examined the role of working memory in processing sentences and discourses of various lengths. In Experiment 1, 10 memory impaired patients with probable Alzheimers disease (AD) and 10 healthy elderly control participants showed similar sensitivity to violations of subject-verb number agreement in a short sentence condition and similar degradation to this sensitivity in a long sentence condition. Performance in neither length condition correlated with performance on working memory tasks, suggesting that the processes involved in interpreting a grammatical dependency between adjacent and nonadjacent elements are different from those required in the working memory tasks. In Experiment 2, the same 10 AD patients were less sensitive than the 10 control participants to pronounantecedent number agreement violations in a short discourse condition, but neither group was affected by additional length. In this experiment, performance in both the short and long conditions correlated with working memory performance. These results show that grammatical and discourse dependencies pose different memory and processing demands, and that these differences are not simply due to differences in the amount of intervening material between dependent words. The results also suggest that while the working memory deficits characteristic of AD do not interfere with on-line grammatical processing within sentences, they do compromise on-line discourse processing across sentences.

Repeated Names, Overt Pronouns, and Null Pronouns in Spanish

In two self-paced, sentence-by-sentence reading experiments we examined the difference in the processing of Spanish discourses with repeated names, overt pronouns, and null pronouns in emphatic and nonemphatic contexts. In Experiment 1, repeated names and overt pronouns caused a processing delay when they referred to salient antecedents in nonemphatic contexts. In Experiment 2, both processing delays were eliminated when an emphatic cleft-structure was used. The processing delay caused by overt pronouns referring to salient antecedents in nonemphatic contexts in Spanish contrasts with previous findings in Chinese, where null and overt pronouns elicited similar reading times. We explain both our Spanish findings and the Chinese findings in a unified framework based on the notion of balance between processing cost and discourse function in line with the informational load hypothesis.

Reasoning versus text processing in the Wason selection task: A nondeontic perspective on perspective effects

We argue that perspective effects in the Wason four-card selection task are a product of the linguistic interpretation of the rule in the context of the problem text and not of the reasoning process underlying card selection. In three experiments, participants recalled the rule they used in either a selection or a plausibility rating task. The results showed that (1) participants tended to recall rules compatible with their card selection and not with the rule as stated in the problem and (2) recall was not affected by whether or not participants performed card selection. We conclude that perspective effects in the Wason selection task do not concern how card selection is reasoned about but instead reflect the inferential text processing involved in the comprehension of the problem text. Together with earlier research that showed selection performance in nondeontic contexts to be indistinguishable from selection performance in deontic contexts (Almor & Sloman, 1996; Sperber, Cara, & Girotto, 1995), the present results undermine the claim that reasoning in a deontic context elicits specialized cognitive processes.

What is in a name? Spatial brain circuits are used to track discourse references.

Pronouns are commonly used instead of explicitly repeating a name, and, in many cases, we comprehend language faster when pronouns are used instead of repetitive references. This is surprising because pronouns are often ambiguous, whereas repeated names provide precise reference. We used functional MRI to investigate the neural correlates of this paradoxical preference. Reading repeated names elicited more activation than pronouns in the middle and inferior temporal gyri and intraparietal sulcus. The temporal lobe activation suggests that repeated names but not pronouns evoke multiple representations that have to be integrated. The intraparietal sulcus activation suggests that this integration relies on brain regions used for spatial attention and perceptual integration.

Interference between conversation and a concurrent visuomotor task

We report 2 experiments during which participants conversed with either a confederate (Experiment 1) or a close friend (Experiment 2) while tracking a moving target on a computer screen. In both experiments, talking led to worse performance on the tracking task than listening. We attribute this finding to the increased cognitive demands of speech planning and monitoring. Growth curve analyses of task performance during the beginning and end of conversation segments revealed dynamical changes in the impact of conversation on visuomotor task performance, with increasing impact during the beginning of speaking segments and decreasing impact during the beginning of listening segments. At the end of speaking and listening segments, this pattern reversed. These changes became more pronounced with increased difficulty of the task. Together, these results show that the planning and monitoring aspects of conversation require the majority of the attentional resources that are also used for nonlinguistic visuomotor tasks. The fact that similar results were obtained when conversing with both a confederate and a friend indicates that our findings apply to a wide range of conversational situations. This is the first study to show the fine-grained time course of the shifting attentional demands of conversation on a concurrently performed visuomotor task.

Teasing Apart the Contribution of Memory and Language Impairments in Alzheimer's Disease: An Online Study of Sentence Comprehension

Sentence comprehension is a complex activity that depends on many different component skills, including the ability to understand individual words, integrate the meanings of adjacent words, and int...

Focus and noun phrase anaphors in spoken language comprehension

Two experiments employed a lexical decision task and a delayed cued recall task to investigate whether and how syntactic focusing affects the online processing and long-term encoding of repeated and non-repeated definite NP anaphors in spoken language comprehension. For discourses with repeated anaphors (Experiment 1), focus facilitated lexical decisions but resulted in poorer recall performance. Discourses with non-repeated anaphors (Experiment 2) showed focus facilitation in lexical decision but no effects in recall. These results show that, similar to reading, spoken language comprehension is impeded by repeated reference to a focused discourse referent. The finding that repetition initially facilitates processing but then interferes with the resulting memory representation is consistent with theories that view referential processing as consisting of multiple stages that can be differentially impacted by repetition.