Paul Whitney

Impulsive decision making and working memory.

Decision making that favors short-term over long-term consequences of action, defined as impulsive or temporally myopic, may be related to individual differences in the executive functions of working memory (WM). In the first 2 experiments, participants made delay discounting (DD) judgments under different WM load conditions. In a 3rd experiment, participants high or low on standardized measures of imupulsiveness and dysexecutive function were asked to make DD judgments. A final experiment examined WM load effects on DD when monetary rewards were real rather than hypothetical. The results showed that higher WM load led to greater discounting of delayed monetary rewards. Further, a strong direct relation was found between measures of impulsiveness, dysexecutive function,and discounting of delayed rewards. Thus, limits on WM function, either intrinsic or extrinsic, are predictive of a more impulsive decision-making style.

Somatic markers, working memory, and decision making

The somatic marker hypothesis formulated by Damasio (e.g., 1994; Damasio, Tranel, & Damasio, 1991) argues that affective reactions ordinarily guide and simplify decision making. Although originally intended to explain decision-making deficits in people with specific frontal lobe damage, the hypothesis also applies to decision-making problems in populations without brain injury. Subsequently, the gambling task was developed by Bechara (Bechara, Damasio, Damasio, & Anderson, 1994) as a diagnostic test of decision-making deficit in neurological populations. More recently, the gambling task has been used to explore implications of the somatic marker hypothesis, as well as to study suboptimal decision making in a variety of domains. We examined relations among gambling task decision making, working memory (WM) load, and somatic markers in a modified version of the gambling task. Increased WM load produced by secondary tasks led to poorer gambling performance. Declines in gambling performance were associated with the absence of the affective reactions that anticipate choice outcomes and guide future decision making. Our experiments provide evidence that WM processes contribute to the development of somatic markers. If WM functioning is taxed, somatic markers may not develop, and decision making may thereby suffer.

Working‐memory capacity and the use of elaborative inferences in text comprehension

The purpose of this research was to determine if individual differences in working‐memory capacity are related to the ways readers use inferences to facilitate text comprehension. Two groups of subjects, who differed in working‐memory span, read difficult narrative passages a few sentences at a time. The subjects furnished “thinking out loud” protocols of their emerging interpretations. Idea units from the subjects’ protocols were categorized with particular attention to those idea units that expressed a general or specific elaborative inference. Several differences between the two groups of subjects emerged. Low‐memory‐span subjects produced significantly more specific elaborations than the high‐span readers. In addition, most of the specific elaborations that were produced by the high‐span readers were toward the end of a passage. Low‐span readers had a more even distribution of specific elaborations throughout their protocols. Thus, readers with adequate working‐memory capacity can keep their interpret...

The effect of trait anxiety and situational stress on working memory capacity

Abstract Individuals were divided into high and low trait anxiety groups and were exposed to 10 min of a stressful environment (a video game competition) or a nonstressful environment. Their subsequent performance on word span and reading span tasks was examined. Unlike the word span task, which measures short-term storage capacity, the reading span task measures storage and manipulation capacity. No differences between groups were found on word span performance. In contrast, there were interactive effects of trait anxiety and situational stress on reading span performance. The performance of the high anxiety subjects decreased in the stressful condition. However, the high anxiety subjects performed better than the low anxiety subjects in the nonstressful condition. These data provide direct evidence for changes in working memory capacity resulting from the joint effects of trait anxiety and situational stress.

Components of Working Memory and Somatic Markers in Decision Making

According to Damasio’s somatic marker hypothesis, affective reactions ordinarily guide and simplify decision making. In an earlier study, we used a modified version of the gambling task developed by Bechara and colleagues so that we could explore the relations among decision making, working memory (WM) load, and formation of somatic markers. This prior work found that an increased WM load produced by secondary tasks interfered with the development of somatic markers and led to poorer gambling task performance. In the present study, we tested whether secondary tasks affect the executive functions of WM, verbal buffering, or both. Our findings indicate that verbal buffering alone does not interfere with gambling task performance or the development of somatic markers. Interference with the executive functions of WM is necessary to disrupt gambling performance and somatic markers.

Semantic activation of noun concepts in context

A modified Stoop procedure was used to examine the role that context plays in guiding semantic access of unambiguous nouns in sentence contexts. The sentences either emphasized a high- or a low-dominant property of a noun that was the last word in the sentence or were control sentences. Each sentence was followed by the relevant high- or low-dominant property either immediately or after a 300-or 600-ms delay. There was significant color-naming interference (relative to control) for high-dominant properties regardless of biasing context in the immediate and delayed conditions. There was also significant color-naming interference for low-dominant properties in the immediate condition regardless of context. However, in the delayed conditions, the low-dominant properties led to color-naming interference only when preceded by sentence contexts biasing interpretation toward the low-dominant property. It was concluded that high-dominant properties function as core, or invariant, aspects of meaning and that initial semantic access is context independent.

Deconstructing and reconstructing cognitive performance in sleep deprivation

Mitigation of cognitive impairment due to sleep deprivation in operational settings is critical for safety and productivity. Achievements in this area are hampered by limited knowledge about the effects of sleep loss on actual job tasks. Sleep deprivation has different effects on different cognitive performance tasks, but the mechanisms behind this task-specificity are poorly understood. In this context it is important to recognize that cognitive performance is not a unitary process, but involves a number of component processes. There is emerging evidence that these component processes are differentially affected by sleep loss. Experiments have been conducted to decompose sleep-deprived performance into underlying cognitive processes using cognitive-behavioral, neuroimaging and cognitive modeling techniques. Furthermore, computational modeling in cognitive architectures has been employed to simulate sleep-deprived cognitive performance on the basis of the constituent cognitive processes. These efforts are beginning to enable quantitative prediction of the effects of sleep deprivation across different task contexts. This paper reviews a rapidly evolving area of research, and outlines a theoretical framework in which the effects of sleep loss on cognition may be understood from the deficits in the underlying neurobiology to the applied consequences in real-world job tasks.

Individual differences in working memory strategies for reading expository text

This study investigated whether individual differences in working memory (WM) span are associated with different WM management strategies during the reading of expository text. In Experiment 1, probe questions were presented on line during reading to determine whether thematic information was maintained in WM throughout comprehension. The data indicated that readers across the range of WM span maintained thematic information in WM throughout the reading of a given passage. In Experiment 2, sentence reading times and accuracy for both topic and detail questions were measured in two conditions: when topic sentences were present and when topic sentences were absent. Subjects performed similarly across the range of WM span in the topic-present condition, but lower span subjects performed more poorly on detail questions in the topic-absent condition. In Experiment 3, the topic-present condition of the second experiment was replicated, except that subjects expected to receive questions about details only. Thematic processing and retention of topic and detail information all increased with span. Taken together, these results suggest that, for more difficult text processing tasks, high- and low-span subjects adopt different WM management strategies and these strategies influence what is learned from reading the text.

Think-Aloud Protocols and the Study of Comprehension.

Although the think‐aloud method (TAM) is being used with increasing frequency in the study of text comprehension, many researchers remain skeptical of its value. In this article, we discuss assumptions behind TAM, the specific aspects of comprehension that it can reveal, as well as new directions for research that use TAM. In particular, we argue that TAM is a useful technique for tracking changes in the contents of working memory during comprehension, but we need new approaches to protocol analysis and more research on the relation between the verbal protocols and other assessments of discourse representations.

The effect of foregrounding on readers' use of predictive inferences

This research extends previous attempts to determine whether subjects make predictive inferences during comprehension. For example, when subjects read a passage about someone falling out of a 14th-story window, do they infer that the person is dead? Previous research in which lexical decision, word naming, and recognition tasks have been used for detecting predictive inferences has had mixed results. In experiment 1, a word-stem completion task was used to test for predictive inferences. The word stems were formed from target inferences that followed either priming or control passages. The data revealed that predictive inferences are generated only about concepts that are foregrounded in the passages. In Experiments 2 and 3, lexical decision and naming were used to test for predictive inferences. The lexical decision data replicated the word-stem completion data. A control experiment ruled out a simple context-checking explanation for the lexical decision results. The naming data indicated that this tasks was not sensitive to elaborative inference generation. Theresults show that readers make predictive inferences, but do so selectively.