John M. Hinson

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.

Sensitization–habituation may occur during operant conditioning.

Operant response rates often change within experimental sessions, sometimes increasing and then decreasing. The authors attribute these changes to sensitization and habituation to aspects of the experimental situation presented repeatedly (e.g., reinforcers) or for a prolonged time (e.g., the experimental enclosure). They describe several empirical similarities between sensitization-habituation and within-session changes in operant responding. They argue that many alternative explanations for within-session changes in operant responding can be dismissed. They also examine some implications of linking the literatures on habituation and operant responding. Because responding follows a similar pattern in several other cases (e.g., human vigilance, classical conditioning, and unconditioned responding), 2 relatively simple processes may be responsible for the temporal patterning of behavior in a wide variety of situations. We observed large changes in response rate within experimental sessions when subjects (e.g., rats) responded on operant conditioning procedures (e.g., McSweeney, Hatfield, & Allen, 1990). In many of our experiments, response rates increased to a peak and then decreased. In other experiments, response rates increased without decreasing or decreased without increasing. Figure 1 contains an example of each of these types of changes. The top represents results for rats pressing levers on multiple variable interval (VI) 60-s VI 60-s schedules; the middle, the results for rats pressing levers on a VI 15-s schedule; and the bottom, the results for pigeons pecking keys on a variable ratio (VR) 15 schedule. Each graph represents the proportion of total-session responses during successive 5-min intervals in the session. Throughout this article, we calculated proportions by dividing the number of responses during a 5-min interval by the total number of responses during the session. Although within-session changes in operant responding have been observed in the past (e.g., McSweeney & Roll, 1993), these changes have been treated as problems to control by procedures, such as giving warmup trials (e.g., Hodos & Bonbright, 1972) or time to adapt to the apparatus (e.g., Papini & Overmier, 1985), rather than as phenomena to study. Further consideration suggests that within-session changes deserve study in

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.

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.

Range and sequence effects in judgment

Listeners classified three tones that differed in loudness. Two tones were always similar in intensity (2 dB separation). The third tone was either similar to or different from these two tones. Performance depended on this stimulus range: The greater the difference between two tones fixed in intensity and the third tone, the less precise was the discrimination between the two fixed tones. Performance also depended on sequence: Successive responses were positively correlated. The results show that measures of discriminability depend on stimulus range, and that measures of criterion placements change from trial to trial and depend on stimulus sequence.

Framing Effects under Cognitive Load: The Role of Working Memory in Risky Decisions

Framing effects occur in a wide range of laboratory and natural decision contexts, but the underlying processes that produce framing effects are not well understood. We explored the role of working memory (WM) in framing by manipulating WM loads during risky decisions. After starting with a hypothetical stake of money, participants were then presented a lesser amount that they could keep for certain (positive frame) or lose for certain (negative frame). They made a choice between the sure amount and a gamble in which they could either keep or lose all of the original stake. On half of the trials, the choice was made while maintaining a concurrent WM load of random letters. In both load and no-load conditions, we replicated the typical finding of risk aversion with positive frames and risk seeking with negative frames. In addition, people made fewer decisions to accept the gamble under conditions of higher cognitive load. The data are congruent with a dual-process reasoning framework in which people employ a heuristic to make satisfactory decisions with minimal effort.

Feedback blunting: total sleep deprivation impairs decision making that requires updating based on feedback

STUDY OBJECTIVES To better understand the sometimes catastrophic effects of sleep loss on naturalistic decision making, we investigated effects of sleep deprivation on decision making in a reversal learning paradigm requiring acquisition and updating of information based on outcome feedback. DESIGN Subjects were randomized to a sleep deprivation or control condition, with performance testing at baseline, after 2 nights of total sleep deprivation (or rested control), and following 2 nights of recovery sleep. Subjects performed a decision task involving initial learning of go and no go response sets followed by unannounced reversal of contingencies, requiring use of outcome feedback for decisions. A working memory scanning task and psychomotor vigilance test were also administered. SETTING Six consecutive days and nights in a controlled laboratory environment with continuous behavioral monitoring. SUBJECTS Twenty-six subjects (22-40 y of age; 10 women). INTERVENTIONS Thirteen subjects were randomized to a 62-h total sleep deprivation condition; the others were controls. MEASUREMENTS AND RESULTS Unlike controls, sleep deprived subjects had difficulty with initial learning of go and no go stimuli sets and had profound impairment adapting to reversal. Skin conductance responses to outcome feedback were diminished, indicating blunted affective reactions to feedback accompanying sleep deprivation. Working memory scanning performance was not significantly affected by sleep deprivation. And although sleep deprived subjects showed expected attentional lapses, these could not account for impairments in reversal learning decision making. CONCLUSIONS Sleep deprivation is particularly problematic for decision making involving uncertainty and unexpected change. Blunted reactions to feedback while sleep deprived underlie failures to adapt to uncertainty and changing contingencies. Thus, an error may register, but with diminished effect because of reduced affective valence of the feedback or because the feedback is not cognitively bound with the choice. This has important implications for understanding and managing sleep loss-induced cognitive impairment in emergency response, disaster management, military operations, and other dynamic real-world settings with uncertain outcomes and imperfect information.

Measurement of cognition in studies of sleep deprivation

Controlled laboratory studies of the effects of sleep deprivation on cognition have the potential to further our understanding of why some complex tasks are more affected by lack of sleep than other tasks. However, apparently simple cognitive tasks reflect multiple cognitive processes at once. Some of the component processes involved in a task may be more affected by sleep deprivation than others. Thus, interpreting measures of overall performance without consideration of the specific task requirements can lead to misleading conclusions. Using examples from studies of attention, working memory and executive functioning, we demonstrate the importance of analysing how different task components contribute to performance and how the nature of the stimulus content can influence outcomes of sleep deprivation studies. Recent developments in cognitive neuropsychology may help sleep researchers conduct more precise tests of fatigue effects on cognition. In turn, studies of sleep and cognition hold promise as a strategy for the development of better general models of how the cognitive system adjusts dynamically to impairments in processing.

Affective biasing of choices in gambling task decision making

The proponents of the somatic marker hypothesis presume that rational decision making is guided by emotional reactions that are developed from prior experience. Supporting evidence for the hypothesis comes almost exclusively from the short-term affective reactions that are learned during the course of a hypothetical decision-making task—the gambling task (GT). We examined GT performance and affective reactions to choices when those choices were biased by words that had preexisting affective value. In one experiment, affectively valued words directly signaled good and bad choices. A congruent relation between affective value of word and choice outcome improved GT performance, whereas an incongruent relation greatly interfered with performance. In another experiment, affectively valued words were maintained as a working memory (WM) load between GT choices. A WM load with affectively positive words somewhat improved GT performance, whereas affectively negative words interfered with performance. Somatic markers—indicated by differential anticipatory skin conductance response (SCR ) amplitude for good and bad choices—appeared at a point in the GT session when choice performance was superior. However, differential SCR developed during the session after good choice performance was already established. These results indicate that preexisting affective biases can influence GT decision making. In addition, the somatic markers that are regular accompaniments of GT decision making appeared to be temporally lagging indicators of choice performance. 2006 Psychonomic Society, Inc.