Close encounters of the distracting kind: Identifying the cause of visual tracking errors

Why can we track only so many objects? We addressed this question by asking when and how tracking errors emerge. To test the hypothesis that many tracking errors are target/nontarget confusions emerging from close encounters, we compared standard multiple-object tracking trials with trials on which a nontarget turned a random color whenever it approached within 4° of a target. This manipulation significantly improved performance by alleviating the correspondence challenge of a close encounter. Two control experiments showed that color change benefits were not merely due to target recovery. Follow-up experiments demonstrated that color change benefits did not accrue monotonically with distance but, instead, seemed to obey a step function; and an additional experiment demonstrated that, without color changes, the frequency of close encounters predicts tracking performance. Taken together, these experiments suggest that uncertainty about target location imposes the primary constraint on tracking, at times causing errors by leading to confusions between targets and nontargets.     

An observation on the spontaneous noticing of prospective memory event-based cues

In event-based prospective memory, current theories make differing predictions as to whether intention-related material can be spontaneously noticed (i.e., noticed without relying on preparatory attentional processes). In 2 experiments, participants formed an intention that was contextually associated to the final phase of the experiment, and lures that overlapped to differing degrees with the features of the intention-related cues were embedded in the initial phase. When participants were outside of the appropriate responding context (i.e., the initial phase), they exhibited slower latencies to lures that exactly matched the features of their intention compared with other types of lures and control words. In addition, on a final remember/know recognition test, participants reported having greater subjective recollection for the occurrence of the exact-match lures. These results suggest that exact-match lures were spontaneously noticed and differentially processed in the absence of any observable preparatory attentional processes. The findings have implications for the theoretical debate over whether preparatory attention must always be relied upon to notice intention-related material.     

Reevaluation of Piaget’s concept of egocentrism: New perspectives on a misunderstood idea

The paper states the goal of this special issue and briefly summarizes the topics of the papers addressed in this issue.     

Towards mouse models of perseveration: a heritable component in extinction of operant behavior in fourteen standard and recombinant inbred mouse lines

Extinction of instrumental responses is an essential skill for adaptive behavior such as foraging. So far, only few studies have focused on extinction following appetitive conditioning in mice. We studied extinction of appetitive operant lever-press behavior in six standard inbred mouse strains (A/J, C3H/HeJ, C57BL/6J, DBA/2J, BALB/cByJ and NOD/Ltj) and eight recombinant inbred mouse lines. From the response rates at the end of operant and extinction training we computed an extinction index, with higher values indicating better capability to omit behavioral responding in absence of reward. This index varied highly across the mouse lines tested, and the variability was partially due to a significant heritable component of 12.6%.To further characterize the relationship between operant learning and extinction, we calculated the slope of the time course of extinction across sessions. While many strains showed a considerable capacity to omit responding when lever pressing was no longer rewarded, we found a few lines showing an abnormally high perseveration in lever press behavior, showing no decay in response scores over extinction sessions.No correlation was found between operant and extinction response scores, suggesting that appetitive operant learning and extinction learning are dissociable, a finding in line with previous studies indicating that these forms of learning are dependent on different brain areas. These data shed light on the heritable basis of extinction learning and may help develop animal models of addictive habits and other perseverative disorders, such as compulsive food seeking and eating.     

High-fat diets impair spatial learning in the radial-arm maze in mice

It has been suggested that hyperglycemia and insulin resistance triggered by energy-dense diets can account for hippocampal damage and deficits of cognitive behaviour. We wonder if the impairment of learning and memory processes detected in diet-induced obese (DIO) mice is linked to diet composition itself. With this purpose we have evaluated learning performance in mice undergoing a short-term high-fat (HF) treatment, which leads to a pre-obese state characterized by increased adiposity without significant changes of glucose and insulin plasma levels. C57BL/6J mice were fed either a HF (45 kcal% from fat) or control diet (10 kcal% from fat) during 8 weeks. Learning performance was evaluated by using the four-arm baited version of the eight-arm radial maze test (RAM). Mice were trained to learn the RAM protocol and then memory was tested at different time-points. Time spent to consume food placed in baited arms and errors committed to find them were measured in all sessions. DIO mice significantly spent more time in learning the task and made a greater number of errors than controls. Moreover, retention tests revealed that both working and total memory errors were also more numerous in DIO mice. The current results show that short-term DIO impairs spatial learning and suggest that impairment of hippocampal learning elicited by HF diets might be perceptible before metabolic alterations linked to obesity develop.     

Experiences and perspectives of African American, Latina/o, Asian American, and European American psychology graduate students: A national study

A national, Web-based survey of 1,219 African American, Latina/o, Asian American, and European American psychology graduate students revealed both similarities and differences in experiences and perspectives. Mentoring was found to be the strongest predictor of satisfaction across groups. Academic supports and barriers, along with perceptions of diversity within the academic environment, were also important predictors of satisfaction. Students of color perceived less fairness of representation of their ethnic group within psychology than European American students, and a greater linkage between aspects of the graduate school experience and their ethnicity. Limitations of the study and implications for future research and action are discussed.     

Communication in social networks: Effects of kinship,network size,and emotional closeness

Communication is important in preventing social relationships from decaying over time. This study examined the effects of social network size, emotional closeness, and type of relationship (kinship vs. friendship) on communication patterns in the social networks of 251 women. Participants with large kin networks had longer times to last contact to both kin and friends. Participants with high levels of emotional closeness in their networks had shorter times to last contact. The effect of emotional closeness on time to last contact was greater for kin than for friends. These results demonstrate that time to last contact is closely tied to emotional closeness and suggest that the costs of maintaining kin relationships are lower than the costs of maintaining friendships.     

Friend or foe? The role of latent inhibition in predator and non-predator labelling by coral reef fishes

In communities of high biodiversity, the ability to distinguish predators from non-predators is crucial for prey success. Learning often plays a vital role in the ability to distinguish species that are threatening from those that are not. Many prey animals learn to recognise predators based on a single conditioning event whereby they are exposed to the unknown predator at the same time as alarm cues released from injured conspecifics. The remarkable efficiency of such learning means that recognition mistakes may occur if prey inadvertently learn that a species is a predator when it is not. Latent inhibition is a means by which prey that are pre-exposed to an unknown species in the absence of negative reinforcement can learn that the unknown animal is likely not a threat. Learning through latent inhibition should be conservative because mistakenly identifying predators as non-predators can have fatal consequences. In this study, we demonstrated that a common coral reef fish, lemon damselfish, Pomacentrus moluccensis can learn to recognise a predator as non-threatening through latent inhibition. Furthermore, we showed that we could override the latent inhibition effect by conditioning the prey to recognise the predator numerous times. Our results highlight the ability of prey fish to continually update the information regarding the threat posed by other fishes in their vicinity.