Evidence for a fixed capacity limit in attending multiple locations

A classic question concerns whether humans can attend multiple locations or objects at once. Although it is generally agreed that the answer to this question is “yes,” the limits on this ability are subject to extensive debate. According to one view, attentional resources can be flexibly allocated to a variable number of locations, with an inverse relationship between the number of selected locations and the quality of information processing at each location. Alternatively, these resources might be quantized in a “discrete” fashion that enables concurrent access to a small number of locations. Here, we report a series of experiments comparing these alternatives. In each experiment, we cued participants to attend a variable number of spatial locations and asked them to report the orientation of a single, briefly presented target. In all experiments, participants’ orientation report errors were well-described by a model that assumes a fixed upper limit in the number of locations that can be attended. Conversely, report errors were poorly described by a flexible-resource model that assumes no fixed limit on the number of locations that can be attended. Critically, we showed that these discrete limits were predicted by cue-evoked neural activity elicited before the onset of the target array, suggesting that performance was limited by selection processes that began prior to subsequent encoding and memory storage. Together, these findings constitute novel evidence supporting the hypothesis that human observers can attend only a small number of discrete locations at an instant.     

Weak ventral striatal responses to monetary outcomes predict an unwillingness to resist cigarette smoking

As a group, cigarette smokers exhibit blunted subjective, behavioral, and neurobiological responses to nondrug incentives and rewards, relative to nonsmokers. Findings from recent studies suggest, however, that there are large individual differences in the devaluation of nondrug rewards among smokers. Moreover, this variability appears to have significant clinical implications, since reduced sensitivity to nondrug rewards is associated with poorer smoking cessation outcomes. Currently, little is known about the neurobiological mechanisms that underlie these individual differences in the responsiveness to nondrug rewards. Here, we tested the hypothesis that individual variability in reward devaluation among smokers is linked to the functioning of the striatum. Specifically, functional magnetic resonance imaging was used to examine variability in the neural response to monetary outcomes in nicotine-deprived smokers anticipating an opportunity to smoke—circumstances found to heighten the devaluation of nondrug rewards by smokers in prior work. We also investigated whether individual differences in reward-related brain activity in those expecting to have access to cigarettes were associated with the degree to which the same individuals subsequently were willing to resist smoking in order to earn additional money. Our key finding was that deprived smokers who exhibited the weakest response to rewards (i.e., monetary gains) in the ventral striatum were least willing to refrain from smoking for monetary reinforcement. These results provide evidence that outcome-related signals in the ventral striatum serve as a marker for clinically meaningful individual differences in reward-motivated behavior among nicotine-deprived smokers.     

Competence in everyday activities as a predictor of cognitive risk and mortality

This study examined the association of a performance-based measure of everyday functioning with clinically meaningful outcomes. Elderly participants in a prospective study of dementia were assessed at two occasions on the Everyday Problems Test for Cognitively Challenged Elderly (EPCCE), a performance-based measure of everyday functioning. Older adults who remained cognitively intact performed approximately 0.66 SD units higher on the EPCCE at both occasions than elders rated as impaired, when covarying on age, education, gender, and cognitive status. Relative to the nonimpaired participants, decline in EPCCE performance over a 2-year interval was significantly greater for impaired participants and those participants who transitioned from nonimpaired to impaired over the course of the study. Increased risk of mortality was associated with lower baseline scores and decline in EPCCE performance even after controlling for demographic variables and performance on the Mini-Mental State Examination. Given the clinical importance of identifying "at risk" elders for impairment, the findings from this study provide initial evidence for the predictive utility of performance-based measures of everyday functioning.     

Tendency to catastrophize somatic sensations: pain catastrophizing and anxiety sensitivity in predicting headache

General catastrophic thinking styles about uncomfortable bodily sensations may predispose the development of common health pathologies, such as persistent headache. The purpose of this research was to explore the relationships between the Pain Catastrophizing (PC) Scale and Anxiety Sensitivity (AS) Index, which measure tendencies to catastrophize pain- and anxiety-related somatic sensations, respectively. A non-clinical sample completed the PC Scale, AS Index, and health outcome questionnaires regarding headache (n = 1018). Results revealed that: (i) AS and PC are empirically separate constructs; (ii) the overlap between PC and AS lies within the domain of fearing physical catastrophe; (iii) AS independently predicts weekly headache, headache pain intensity, and the number of a wide range of physical symptoms associated with headache; and (iv) PC independently predicts the presence of weekly headache. Limitations and implications of this research, as well as recommendations for future research directions are discussed.     

Mental imagery, reasoning, and blindness

Although reasoning seems to be inextricably linked to seeing in the “mind's eye”, the evidence is equivocal. In three experiments, sighted, blindfolded sighted, and congenitally totally blind persons solved deductive inferences based on three sorts of relation: (a) visuo-spatial relations that are easy to envisage either visually or spatially, (b) visual relations that are easy to envisage visually but hard to envisage spatially, and (c) control relations that are hard to envisage both visually and spatially. In absolute terms, congenitally totally blind persons performed less accurately and more slowly than the sighted on all such tasks. In relative terms, however, the visual relations in comparison with control relations impeded the reasoning of sighted and blindfolded participants, whereas congenitally totally blind participants performed the same with the different sorts of relation. We conclude that mental images containing visual details that are irrelevant to an inference can even impede the process of reasoning. Persons who are blind from birth—and who thus do not tend to construct visual mental images—are immune to this visual-impedance effect.     

Visuospatial tasks suppress craving for cigarettes

The Elaborated Intrusion (EI) theory of desire posits that visual imagery plays a key role in craving. We report a series of experiments testing this hypothesis in a drug addiction context. Experiment 1 showed that a mental visual imagery task with neutral content reduced cigarette craving in abstaining smokers, but that an equivalent auditory task did not. The effect of visual imagery was replicated in Experiment 2, which also showed comparable effects of non-imagery visual working memory interference. Experiment 3 showed that the benefit of visual over auditory interference was not dependent upon imagery being used to induce craving. Experiment 4 compared a visuomotor task, making shapes from modeling clay, with a verbal task (counting back from 100), and again showed a benefit of the visual over the non-visual task.We conclude that visual imagery supports craving for cigarettes. Competing imagery or visual working memory tasks may help tackle craving in smokers trying to quit.     

Just the thought of it!: Effects of anticipating computer-mediated communication on gender stereotyping

A study investigated how anticipated communication mode affects the use of stereotypes in forming impressions and making task assignments. Participants rated male or female targets with whom they envisioned working on a business project using computer-mediated or face-to-face modes of communication. Results indicated that both men and women were characterized more stereotypically when participants anticipated working with them electronically than when they anticipated working with them face-to-face. Furthermore, task assignments were more often gender stereotype consistent when the communication mode was computer-mediated than when it was face-to-face. These findings suggest that the mere anticipation of computer-mediated communication, without the actual the experience of it, is enough to promote stereotypes and biased decision-making.