Spatial working memory and inhibition of return

Recently we showed that maintaining a location in spatial working memory affects saccadic eye movement trajectories, in that the eyes deviate away from the remembered location (Theeuwes, Olivers, & Chizk, 2005). Such saccade deviations are assumed to be the result of inhibitory processes within the oculomotor system. The present study investigated whether this inhibition is related to the phenomenon of inhibition of return (IOR), the relatively slow selection of previously attended locations as compared with new locations. The results show that the size of IOR to a location was not affected by whether or not the location was kept in working memory, but the size of the saccade trajectory deviation was affected. We conclude that inhibiting working memory-related eye movement activity is not the same as inhibiting a previously attended location in space.     

Input-specific long-term potentiation in the rat lateral amygdala of horizontal slices

Long-term potentiation (LTP) at input synapses to the lateral nucleus of the amygdala (LA) is a candidate mechanism for memory storage during fear learning. Cellular mechanisms of LTP have been nearly exclusively investigated in coronal brain slices. In our experiments, we used a horizontal brain slice preparation of rats that preserved most of the connections to cortical areas and the hippocampus. The stimulation electrodes were located either within the external capsule (EC) or the LA. The aim of the present study was to investigate the mechanisms of LTP induced either by weak theta burst stimulation (TBS) or strong high frequency stimulation (HFS) using the two different stimulation sites. Whereas both TBS and HFS of afferences running through the LA induced stable LTP, TBS failed to induce LTP of EC-inputs to the LA. The present findings also show that LTP in the LA exhibits vulnerability at different time windows after induction. The time window was dependent on the kind of stimulated afferences. Later LTP becomes resistant to disruption by low frequency stimulation. We could show that both used inputs depended on NMDA receptors for LTP-induction. LTP induced by stimulation of fibers within the LA was not altered by nifedipine (10 microM). In contrast, EC-induced LTP was dependent on L-type voltage-gated calcium channels (VGCC). Finally, we found a higher magnitude of LTP in females using TBS, whereas HFS did not cause gender-specific differences. Our study supports the conclusion that the form of LA-LTP depend on which afferences are activated and what pattern of stimulation is used to induce LTP.     

Development of multisensory spatial integration and perception in humans

Previous studies have shown that adults respond faster and more reliably to bimodal compared to unimodal localization cues. The current study investigated for the first time the development of audiovisual (A-V) integration in spatial localization behavior in infants between 1 and 10 months of age. We observed infants' head and eye movements in response to auditory, visual, or both kinds of stimuli presented either 25 degrees or 45 degrees to the right or left of midline. Infants under 8 months of age intermittently showed response latencies significantly faster toward audiovisual targets than toward either auditory or visual targets alone They did so, however, without exhibiting a reliable violation of the Race Model, suggesting that probability summation alone could explain the faster bimodal response. In contrast, infants between 8 and 10 months of age exhibited bimodal response latencies significantly faster than unimodal latencies for both eccentricity conditions and their latencies violated the Race Model at 25 degrees eccentricity. In addition to this main finding, we found age-dependent eccentricity and modality effects on response latencies. Together, these findings suggest that audiovisual integration emerges late in the first year of life and are consistent with neurophysiological findings from multisensory sites in the superior colliculus of infant monkeys showing that multisensory enhancement of responsiveness is not present at birth but emerges later in life.     

Strategy variability: How too much of a good thing can hurt performance

Recent research (e.g., Siegler, 1996) has discovered the important and vital role that variability plays among strategy use and development over time. However, as many researchers have pointed out (e.g., Miller, 1993), the majority of the research addressing this issue has focused on the outcomes, rather than on the potentially more informative aspects of variability, strategy development, and the process of adaptation. In this study, we examined the role of variability during strategy development, utilizing a longitudinal method. Thirteen participants were studied over 3 months as they coached a simulated football team. The results suggest that variability plays a major role in adaptive skill acquisition in a dynamic environment--in the direction, however, opposite to that predicted by previous research done with simple static tasks.     

When is search for a static target among dynamic distractors efficient?

Intuitively, dynamic visual stimuli, such as moving objects or flashing lights, attract attention. Visual search tasks have revealed that dynamic targets among static distractors can indeed efficiently guide attention. The present study shows that the reverse case, a static target among dynamic distractors, allows for relatively efficient selection in certain but not all cases. A static target was relatively efficiently found among distractors that featured apparent motion, corroborating earlier findings. The important new finding was that static targets were equally easily found among distractors that blinked on and off continuously, even when each individual item blinked at a random rate. However, search for a static target was less efficient when distractors abruptly varied in luminance but did not completely disappear. The authors suggest that the division into the parvocellular pathway dealing with static visual information, on the one hand, and the magnocellular pathway common to motion and new object onset detection, on the other hand, allows for efficient filtering of dynamic and static information.     

The beneficial effects of additional task load, positive affect, and instruction on the attentional blink

The attentional blink reflects the impaired ability to identify the 2nd of 2 targets presented in close succession--a phenomenon that is generally thought to reflect a fundamental cognitive limitation. However, the fundamental nature of this impairment has recently been called into question by the counterintuitive finding that task-irrelevant mental activity improves attentional blink performance (C. N. L. Olivers & S. Nieuwenhuis, 2005). The present study found a reduced attentional blink when participants concurrently performed an additional memory task, viewed pictures of positive affective content, or were instructed to focus less on the task. These findings support the hypothesis that the attentional blink is due to an overinvestment of attentional resources in stimulus processing, a suboptimal processing mode that can be counteracted by manipulations promoting divided attention.     

Achievement goals and engagement in individual and collective learning activities

The relationship between achievement goals and individual and collective learning activities was examined for 290 university students who completed two questionnaires. One assessed three achievement goals-a mastery goal and two performance goals, namely, approval seeking and advancing. The other questionnaire measured how actively students report engaging in individual and collective learning activities. Regression analyses showed that the adoption of mastery goals was associated with active engagement in both individual and collective learning, while adoption of a performance goal of approval seeking was associated with passive engagement in individual learning activities. These results are discussed in relation to their theoretical implications and in regard to the possible moderating effect of protecting self-worth.     

Major histocompatibility complex alleles, sexual responsivity, and unfaithfulness in romantic couples

Preferences for mates that possess genes dissimilar to one's own at the major histocompatibility complex (MHC), a polymorphic group of loci associated with the immune system, have been found in mice, birds, fish, and humans. These preferences may help individuals choose genetically compatible mates and may adaptively function to prevent inbreeding or to increase heterozygosity and thereby immunocompetence of offspring. MHC-dissimilar mate preferences may influence the psychology of sexual attraction. We investigated whether MHC similarity among romantically involved couples (N= 48) predicted aspects of their sexual relationship. All women in our sample normally ovulated, and alleles at three MHC loci were typed for each person. As the proportion of MHC alleles couples shared increased, women's sexual responsivity to their partners decreased, their number of extrapair sexual partners increased, and their attraction to men other than their primary partners increased, particularly during the fertile phase of their cycles.     

Negative priming is stronger for task-relevant dimensions: Evidence of flexibility in the selective ignoring of distractor information

The finding that in selective attention tasks responses to previously ignored stimuli are usually retarded is known as negative priming (NP). In previous studies it has been suggested that NP can depend on behavioural goals—that is, NP was observed only for task-relevant object dimensions. We extend these findings with two experiments demonstrating that stronger NP can be observed for task-relevant dimensions than for task-irrelevant dimensions (a) even if participants' tasks vary blockwise within an experiment and (b) if behavioural goals vary from trial to trial. These results suggest that selective NP is a much more flexible process than previously assumed.     

A national survey of hospital directors' views about the importance of various chaplain roles: differences among disciplines and types of hospitals

A national random sample of hospital directors was asked to rate the importance of seven categories of chaplain roles and functions: 246 nursing directors, 267 social services directors, 307 medical directors, and 611 pastoral care directors. All four groups rated end-of-life care, prayer, and emotional support as being between very important and extremely important. Other roles, including consultation, advocacy, community outreach, and religious services and rituals were rated significantly less important. Significant differences were found across disciplines and hospital settings (general, psychiatric, etc.). Medical directors rated most chaplain roles lower than other directors did, and directors in psychiatric hospitals rated all roles, except religious services/rituals, lower than their counterparts in other types of hospitals. The importance that directors accorded to all the chaplain roles examined was also influenced by their own spirituality and religiosity, as well as the religious affiliation of their institution.