Beyond heritability: neurotransmitter genes differentially modulate visuospatial attention and working memory

A cued, visuospatial attention task and a working memory task were administered to 89 healthy adults genotyped for a T-to-C polymorphism in CHRNA4, a nicotinic receptor subunit gene. Increasing gene dose of the C allele of the CHRNA4 gene (i.e., no C alleles, one C allele, two C alleles) was associated with increased reaction time (RT) benefits of valid attentional cuing and reduced RT costs of invalid cues, but was not associated with working memory performance. In a second experiment, 103 healthy persons were genotyped for a G-to-A polymorphism of the dopamine beta-hydroxylase (DBH) gene. Increasing gene dose of the G allele of the DBH gene was associated with increased working memory accuracy at a high memory load. However, there was no consistent association between the DBH gene and visuospatial attention. Thus, a double dissociation was observed, with visuospatial attention associated with CHRNA4 but not the DBH gene and, conversely, working memory associated with the DBH gene but not CHRNA4. The results show that normal allelic variations in single neurotransmitter genes modulate individual differences in processing components of cognitive functions in healthy individuals.     

Toddlers' representations of space: the role of viewer perspective

In the present study, we examined how people code object location when an object is hidden in an enclosed space. On object location tasks involving disorientation, viewers must code the location of an object in relation to the spatial environment because they cannot directly track their changing relation to the object. Recently, we showed that viewers also code their perspective relative to the entire space (inside vs. outside) in such tasks. To determine whether viewers code perspective whenever they must locate an object, we examined young children's performance on a task in which coding perspective would be difficult. Our task involved both disorientation and translation (i.e., movement from inside to outside the space or vice versa). When translation preceded disorientation, performance was comparable to performance on tasks with no translation. However, when disorientation preceded translation, performance was at chance. The implications of these findings for location coding are discussed.     

Hypnotic disgust makes moral judgments more severe

Highly hypnotizable participants were given a posthypnotic suggestion to feel a flash of disgust whenever they read an arbitrary word. They were then asked to rate moral transgressions described in vignettes that either did or did not include the disgust-inducing word. Two studies show that moral judgments can be made more severe by the presence of a flash of disgust. These findings suggest that moral judgments may be grounded in affectively laden moral intuitions.     

Teaching pigeons to commit base-rate neglect

Whereas humans display base-rate neglect in a behavioral analogue of the base-rate problem, pigeons have been shown to behave optimally in a comparable task, appropriately weighting base-rate and case-cue information. Previous studies have shown that prior experience may interfere with optimal decisions for human subjects, a result consistent with the position that poor and illogical decisions often follow from the misapplication of learned rules. The present study shows that pigeons will also display base-rate neglect if given extensive pretraining with informative case cues. Two experiments with pigeons, in a matching-to-sample procedure designed to mimic the classic base-rate problem, show that pigeons display base-rate neglect after extensive pretraining with the matching task.     

"Tip of the fingers" experiences by deaf signers: insights into the organization of a sign-based lexicon

The "tip of the fingers" phenomenon (TOF) for sign language parallels the "tip of the tongue" phenomenon (TOT) for spoken language. During a TOF, signers are sure they know a sign but cannot retrieve it. Although some theories collapse semantics and phonology in sign language and thus predict that TOFs should not occur, TOFs were elicited in the current study. Like TOTs, TOFs often resolve spontaneously, commonly involve targets that are proper names, and frequently include partial access to phonology. Specifically, signers were more likely to retrieve a target sign's handshape, location, and orientation than to retrieve its movement. Signers also frequently recalled the first letter of a finger-spelled word. The existence of TOFs supports two-stage retrieval and a division between semantics and phonology in American Sign Language. The partial phonological information available during TOFs suggests that phonological features are accessed more simultaneously during lexical access for signed language than during lexical access for spoken language.     

Visual short-term memory load suppresses temporo-parietal junction activity and induces inattentional blindness

The right temporo-parietal junction (TPJ) is critical for stimulus-driven attention and visual awareness. Here we show that as the visual short-term memory (VSTM) load of a task increases, activity in this region is increasingly suppressed. Correspondingly, increasing VSTM load impairs the ability of subjects to consciously detect the presence of a novel, unexpected object in the visual field. These results not only demonstrate that VSTM load suppresses TPJ activity and induces inattentional blindness, but also offer a plausible neural mechanism for this perceptual deficit: suppression of the stimulus-driven attentional network.     

Using cognitive models to map relations between neuropsychological disorders and human decision-making deficits

Findings from a complex decision-making task (the Iowa gambling task) show that individuals with neuropsychological disorders are characterized by decision-making deficits that lead to maladaptive risk-taking behavior. This article describes a cognitive model that distills performance in this task into three different underlying psychological components: the relative impact of rewards and punishments on evaluations of options, the rate that the contingent payoffs are learned, and the consistency between learning and responding. Findings from 10 studies are organized by distilling the observed decision deficits into the three basic components and locating the neuropsychological disorders in this component space. The results reveal a cluster of populations characterized by making risky choices despite high attention to losses, perhaps because of difficulties in creating emotive representations. These findings demonstrate the potential contribution of cognitive models in building bridges between neuroscience and behavior.     

Secret agents: inferences about hidden causes by 10- and 12-month-old infants

Considerable evidence indicates that preverbal infants expect that only physical contact can cause an inanimate object to move. However, very few studies have investigated infants' expectations about the source of causal power. In three experiments, we found that (a) 10- and 12-month-old infants expect a human hand, and not an inanimate object, to be the primary cause of an inanimate object's motion; (b) infants' expectations can lead them to infer a hidden causal agent without any direct perceptual evidence; and (c) infants do not infer a hidden causal agent if the moving object was previously shown to be capable of self-generated motion.     

Distinctive processing underlies skilled memory

Research on skilled memory has focused on organizational processes to the exclusion of item-specific processes, although theories of skilled memory do acknowledge the importance of both kinds of processes. Using the isolation methodology, we presented lists of American football team names to participants who had either a high or a low level of knowledge about American football. An isolation effect (greater recall of the target in the isolate list than in a homogeneous control list) was observed only with high-knowledge participants. When standard lists were used, an isolation effect was observed with both groups. These findings empirically validate the importance of both organizational and item-specific processing as the basis of distinctive processing underlying skilled memory performance.     

Constructed criteria: redefining merit to justify discrimination

This article presents an account of job discrimination according to which people redefine merit in a manner congenial to the idiosyncratic credentials of individual applicants from desired groups. In three studies, participants assigned male and female applicants to gender-stereotypical jobs. However, they did not view male and female applicants as having different strengths and weaknesses. Instead, they redefined the criteria for success at the job as requiring the specific credentials that a candidate of the desired gender happened to have. Commitment to hiring criteria prior to disclosure of the applicant's gender eliminated discrimination, suggesting that bias in the construction of hiring criteria plays a causal role in discrimination.