Effects of bilateral eye movements on gist based false recognition in the DRM paradigm

The effects of saccadic bilateral (horizontal) eye movements on gist based false recognition was investigated. Following exposure to lists of words related to a critical but non-studied word participants were asked to engage in 30s of bilateral vs. vertical vs. no eye movements. Subsequent testing of recognition memory revealed that those who undertook bilateral eye movement were more likely to correctly recognise previously presented words and less likely to falsely recognise critical non-studied associates. This result joins other research in demonstrating the conditions in which false memory effects can be attenuated.     

Dissimilarity is used as evidence of category membership in multidimensional perceptual categorization: a test of the similarity-dissimilarity generalized context model

In exemplar models of categorization, the similarity between an exemplar and category members constitutes evidence that the exemplar belongs to the category. We test the possibility that the dissimilarity to members of competing categories also contributes to this evidence. Data were collected from two 2-dimensional perceptual categorization experiments, one with lines varying in orientation and length and the other with coloured patches varying in saturation and brightness. Model fits of the similarity-dissimilarity generalized context model were used to compare a model where only similarity was used with a model where both similarity and dissimilarity were used. For the majority of participants the similarity-dissimilarity model provided both a significantly better fit and better generalization, suggesting that people do also use dissimilarity as evidence.     

Order information and free recall: evaluating the item-order hypothesis

The item-order hypothesis proposes that order information plays an important role in recall from long-term memory, and it is commonly used to account for the moderating effects of experimental design in memory research. Recent research (Engelkamp, Jahn, & Seiler, 2003; McDaniel, DeLosh, & Merritt, 2000) raises questions about the assumptions underlying the item-order hypothesis. Four experiments tested these assumptions by examining the relationship between free recall and order memory for lists of varying length (8, 16, or 24 unrelated words or pictures). Some groups were given standard free-recall instructions, other groups were explicitly instructed to use order information in free recall, and other groups were given free-recall tests intermixed with tests of order memory (order reconstruction). The results for short lists were consistent with the assumptions of the item-order account. For intermediate-length lists, explicit order instructions and intermixed order tests made recall more reliant on order information, but under standard conditions, order information played little role in recall. For long lists, there was little evidence that order information contributed to recall. In sum, the assumptions of the item-order account held for short lists, received mixed support with intermediate lists, and received no support for longer lists.     

Social Support Mediates Loneliness and Human Herpesvirus Type 6 (HHV-6) Antibody Titers

The current study investigated the impact of a severe environmental stressor and the role that declining social integration played in mediating its effect on loneliness and immune status. Increased loneliness and decreased social support in the months following the stressor (storm) were significantly associated with increased HHV-6 antibody liters, reflecting poorer control over the virus. Poorer social integration mediated the relationship between loneliness and HHV-6, even after controlling for nonspecific polyclonal B-cell activation, disease status (CD3+CD4+ cell counts), living arrangements, acute social losses (bereavement), and potential disruptions in social-support resources. These findings suggest that specific elements of social support may explain the oft-noted negative effects of loneliness on the immune system, and generalized to a medically vulnerable population.     

Hebb repetition effects in visual memory: the roles of verbal rehearsal and distinctiveness

A version of the Hebb repetition task was used with faces to explore the generality of the effect in a nonverbal domain. In the baseline condition, a series of upright faces was presented, and participants were asked to reconstruct the original order. Performance in this condition was compared to another in which the same stimuli were accompanied by concurrent verbal rehearsal to examine whether Hebb learning is dependent on verbal processing. Baseline performance was also compared to a condition in which the same faces were presented inverted. This comparison was used to determine the importance in Hebb learning of being able to visually distinguish between the list items. The results produced classic serial position curves that were equivalent over conditions with Hebb repetition effects being in evidence only for upright faces and verbal suppression as having no effect. These findings are interpreted as posing a challenge to current models derived from verbal-domain data.     

Correspondence Between Preference Assessment Outcomes and Stimulus Reinforcer Value for Social Interactions

Preferred forms of social interaction were identified using a paired-stimulus format in which two 3–5 s videos of the experimenter providing the social interaction to the participant were presented. Reinforcer efficacy of the high-, medium-, and low-preferred interactions was evaluated using a progressive-ratio schedule to determine the amount of work maintained by the stimuli. Results showed that higher preference stimuli produced larger break points than did lower preference stimuli.     

Chickadees discriminate contingency reversals presented consistently,but not frequently

Chickadees are high-metabolism, non-migratory birds, and thus an especially interesting model for studying how animals follow patterns of food availability over time. Here, we studied whether black-capped chickadees (Poecile atricapillus) could learn to reverse their behavior and/or to anticipate changes in reinforcement when the reinforcer contingencies for each stimulus were not stably fixed in time. In Experiment 1, we examined the responses of chickadees on an auditory go/no-go task, with constant reversals in reinforcement contingencies every 120 trials across daily testing intervals. Chickadees did not produce above-chance discrimination; however, when trained with a procedure that only reversed after successful discrimination, chickadees were able to discriminate and reverse their behavior successfully. In Experiment 2, we examined the responses of chickadees when reversals were structured to occur at the same time once per day, and chickadees were again able to discriminate and reverse their behavior over time, though they showed no reliable evidence of reversal anticipation. The frequency of reversals throughout the day thus appears to be an important determinant for these animals’ performance in reversal procedures.     

Electrophysiological and behavioral evidence reveals the effects of trait anxiety on contingent attentional capture

Few studies have investigated the effects of anxiety on contingent attentional capture. The present study examined contingent attentional capture in trait anxiety by applying a rapid serial visual presentation (RSVP) paradigm during electroencephalographic recording. Overall, the behavioral and electrophysiological results showed a larger capture effect when a distractor was the same color as the target compared to when the distractor was not of the target color. Moreover, high-anxiety individuals showed a larger N2pc in the target colored distractor condition and nontarget colored distractor condition compared to the distractor-absent condition. In addition, the reaction time was slower when distractors were presented in the left visual field compared to when they were in the right visual field. This pattern was not seen in low-anxiety individuals. The findings may indicate that high-anxiety individuals allocate attention to the target less efficiently and have reduced suppression of distractors compared to low-anxiety individuals who could suppress attention to the distractors more efficiently. Future work could valuably investigate the consequences of such differences in terms of benefits and disruption associated with attentional capture differences in a range of anxious populations in different risk monitoring situations.     

Generation and memory for contextual detail

Generation enhances item memory but may not enhance other aspects of memory. In 12 experiments, the author investigated the effect of generation on context memory, motivated in part by the hypothesis that generation produces a trade-off in encoding item and contextual information. Participants generated some study words (e.g., hot-c__) and read others (e.g., hot-cold). Generation consistently enhanced item memory but did not enhance context memory. More specifically, generation disrupted context memory for the color of the target word but did not affect context memory for location, background color, and cue-word color. The specificity of the negative generation effect in context memory argues against a general item-context trade-off. A processing account of generation meets greater success. In addition, the results provide no evidence that generation enhances recollection of contextual details.