What you cannot see can help you: the effect of exposure to unreportable stimuli on approach behavior

We examined effects of exposure to unreportable images of spiders on approach towards a tarantula. Pretests revealed awareness of the stimuli was at chance. Participants high or low (top and bottom 15%) on fear of spiders were randomly assigned to receive computer-generated exposure to unreportable pictures of spiders or outdoor scenes. They then engaged in a Behavioral Approach Task (BAT) with a live tarantula. Non-fearful participants completed more BAT items than spider-fearful individuals. Additionally, as predicted, a significant interaction (F(1,48)=5.12, p<.03) between fear of spiders and stimulus demonstrated that spider-fearful participants exposed to spiders completed more BAT items than spider-fearful participants exposed to control stimuli (but not as many as non-fearful participants). The findings support the hypothesis that exposure to unreportable feared stimuli promotes approach towards the feared object. Future research and clinical implications were discussed.     

Memory enhancement of classical fear conditioning by post-training injections of corticosterone in rats

There is extensive evidence that post-training administration of the adrenocortical hormone corticosterone facilitates memory consolidation processes in a variety of contextual and spatial-dependent learning situations. The present experiments examine whether corticosterone can modulate memory of auditory-cue classical fear conditioning, a learning task that is not contingent on contextual or spatial representations. Male Sprague-Dawley rats received three pairings of a single-frequency auditory stimulus and footshock, followed immediately by a post-training subcutaneous injection of either corticosterone (1.0 or 3.0mg/kg) or vehicle. Retention was tested 24h later in a novel test chamber and suppression of ongoing motor behavior served as the measure of conditioned fear. Corticosterone dose-dependently facilitated suppression of motor activity during the 10-s presentation of the auditory cue. As corticosterone administration did not alter responding after unpaired presentations of tone and shock, tone alone, shock alone or absence of tone/shock, the findings indicated that corticosterone selectively facilitated memory of the tone-shock association. Furthermore, injections of corticosterone given 3h after training did not alter motor activity during retention testing, demonstrating that corticosterone enhanced time-dependent memory consolidation processes. These findings provide evidence that corticosterone modulates the consolidation of memory for auditory-cue classical fear conditioning and are consistent with a wealth of data indicating that glucocorticoids can modulate a wide variety of emotionally influenced memories.     

Habit and skill learning in schizophrenia: evidence of normal striatal processing with abnormal cortical input

Different forms of nondeclarative learning involve regionally specific striatal circuits. The motor circuit (involving the putamen) has been associated with motor–skill learning and the dorsolateral prefrontal cortex (DLPFC) circuit (involving the caudate) has been associated with cognitive–habit learning. Efforts to differentiate functional striatal circuits within patient samples have been limited. Previous studies have provided mixed results regarding striatal-dependent nondeclarative learning deficits in patients with schizophrenia. In this study, a cognitive–habit learning task (probabilistic weather prediction) was used to assess the DLPFC circuit and a motor–skill learning task (pursuit rotor) was used to assess the motor circuit in 35 patients with schizophrenia and 35 normal controls. Patients with schizophrenia displayed significant performance differences from controls on both nondeclarative tasks; however, cognitive–habit learning rate in patients did not differ from controls. There were performance and learning-rate differences on the motor–skill learning task between the whole sample of patients and controls, however, analysis of a subset of patients and controls matched on general intellectual level eliminated learning rate differences between groups. The abnormal performance offset between patients with schizophrenia and controls in the absence of learning rate differences suggests that abnormal cortical processing provides altered input to normal striatal circuitry.     

Age-related differences in the course of cognitive skill acquisition: the role of regional cortical shrinkage and cognitive resources

This study examined the impact of age-related differences in regional cerebral volumes and cognitive resources on acquisition of a cognitive skill. Volumes of brain regions were measured on magnetic resonance images of healthy adults (aged 22-80). At the early stage of learning to solve the Tower of Hanoi puzzle, speed and efficiency were associated with age, prefrontal cortex volume, and working memory. A similar pattern of brain-behavior associations was observed with perseveration measured on the Wisconsin Card Sorting Test. None of the examined structural brain variables were important at the later stages of skill acquisition. When hypertensive participants were excluded, the effect of prefrontal shrinkage on executive aspects of performance was no longer significant, but the effect of working memory remained.     

William James and the unconscious: redressing a century-old misunderstanding

Contrary to received wisdom in psychology, William James did not oppose postulating unconscious processes. This mistaken belief stems from a misreading of a passage in his Principles concerned with disproving the metaphysical notion that mental states are composed of elementary mental units. The term unconscious had been co-opted by individuals who supported this position. Unconscious did not mean then what it means now. Analysis of the rest of the Principles , his later works, and his reactions to the works of others reveals that James actually supported what we would now term unconscious processes. He even contributed to their study with his notions of the "fringe,""habit," and "subconscious incubation." Causes and effects of this misunderstanding are discussed.     

Age-related differences in recognition memory for items and associations: Contribution of individual differences in working memory and metamemory

Ability to form new associations between unrelated items is particularly sensitive to aging, but the reasons for such differential vulnerability are unclear. In this study, we examined the role of objective and subjective factors (working memory and beliefs about memory strategies) on differential relations of age with recognition of items and associations. Healthy adults (N = 100, age 21 to 79) studied word pairs, completed item and association recognition tests, and rated the effectiveness of shallow (e.g., repetition) and deep (e.g., imagery or sentence generation) encoding strategies. Advanced age was associated with reduced working memory (WM) capacity and poorer associative recognition. In addition, reduced WM capacity, beliefs in the utility of ineffective encoding strategies, and lack of endorsement of effective ones were independently associated with impaired associative memory. Thus, maladaptive beliefs about memory in conjunction with reduced cognitive resources account in part for differences in associative memory commonly attributed to aging. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Less is more: the effects of very brief versus clearly visible exposure

This study compared the effects of exposure to masked and unmasked phobic stimuli on phobic behavior. Participants were identified as spider-phobic with a questionnaire and a Behavioral Avoidance Test (BAT) with a live tarantula (N = 101). One week later, they were administered one of three types of exposure: very brief (25 ms) or clearly visible (120 ms) images of spiders, or very brief images of flowers. They reported ratings of subjective distress just before and after these exposures, and engaged in the BAT again thereafter. Two weeks later, 57 participants returned for a follow-up BAT. The results indicated a double dissociation between the effects of very brief and clearly visible exposure: the former reduced avoidance of the tarantula and did not affect distress, whereas the latter increased distress but did not affect avoidance. The behavioral effect lasted for two weeks. These findings suggest that avoidance of a feared object can be reduced without full conscious awareness. The theoretical implications are discussed.     

Genes and the parsing of cognitive processes

Now that the human genome has been sequenced there exists the possibility of identifying specific genes that affect human cognition. In this article, recent studies that have found associations between common gene variants and specific cognitive processes are reviewed. Several principles for evaluating this new field are also discussed. The interpretation of results is far from simple because a single gene can affect multiple processes, multiple genes can impact on a single process, and multiple cognitive processes are intercorrelated. In general, functional neuroimaging has been a more sensitive assay of cognitive processing than behavioral measures used alone, although there are important caveats regarding its use. Replicated findings so far involve associations between a COMT polymorphism and prefrontally-based executive functions and neurophysiology, and a BDNF polymorphism and medial-temporal-cortex based declarative memory processes. Implicit in this review is a concern that many of the cognitive paradigms used evolved for purposes well outside those described here. As such it may be necessary to view cognition in novel ways, based on constraints imposed by genomics and neurobiology, in order to increase the effect size of genotypic influences on cognition.