Apes' use of iconic cues in the object-choice task

In previous studies great apes have shown little ability to locate hidden food using a physical marker placed by a human directly on the target location. In this study, we hypothesized that the perceptual similarity between an iconic cue and the hidden reward (baited container) would help apes to infer the location of the food. In the first two experiments, we found that if an iconic cue is given in addition to a spatial/indexical cue - e.g., picture or replica of a banana placed on the target location - apes (chimpanzees, bonobos, orangutans, gorillas) as a group performed above chance. However, we also found in two further experiments that when iconic cues were given on their own without spatial/indexical information (iconic cue held up by human with no diagnostic spatial/indexical information), the apes were back to chance performance. Our overall conclusion is that although iconic information helps apes in the process of searching hidden food, the poor performance found in the last two experiments is due to apes' lack of understanding of the informative (cooperative) communicative intention of the experimenter.     

Can wild common marmosets (Callithrix jacchus) solve the parallel strings task?

Patterned string tasks are a test of perceptual capacity and the understanding of means-end connections. Primates can solve complex forms of this task in laboratories. However, this may not indicate the level of such cognition that is commonly employed in the wild, where decision-making time is often short and distractions such as predator avoidance and competition between conspecifics are often prevalent. The current study tests whether wild common marmosets (Callithrix jacchus) can successfully complete the simplest form of the patterned string task, parallel strings, while in their natural environment. Although 12 out of 13 marmosets could successfully complete the task, in previous laboratory-based studies on primates, the errors at this task by all primate species tested were consistently lower than in the present study. This is probably explained by the added difficulties imposed by the natural setting of the task in the present study, exemplified by a significant increase in observed vigilance behaviour by subject animals prior to attempts at the task that were unsuccessful. The undertaking of such tasks by common marmosets in situ probably provides a more reasonable representation of the levels of cognitive capacity expressed by this species in the wild than do laboratory-based studies of the task.     

Use or misuse of the selection task? Rejoinder to Fiddick,Cosmides, and Tooby

Sperber, Cara, and Girotto (Cognition 52 (1995) 3) argued that, in Wason's selection task, relevance-guided comprehension processes tend to determine participants' performance and pre-empt the use of other inferential capacities. Because of this, the value of the selection task as a tool for studying human inference has been grossly overestimated. Fiddick, Cosmides, and Tooby (Cognition 77 (2000) 1) argued against Sperber et al. that specialized inferential mechanisms, in particular the "social contract algorithm" hypothesized by Cosmides (Cognition 31 (1989) 187), pre-empt more general comprehension abilities, making the selection task a useful tool after all. We rebut this argument. We argue and illustrate with two new experiments, that Fiddick et al. mix the true Wason selection task with a trivially simple categorization task superficially similar to the Wason task, yielding methodologically flawed evidence. We conclude that the extensive use of various kinds of selection tasks in the psychology of reasoning has been quite counter-productive and should be discontinued.     

Task switching: a PDP model

When subjects switch between a pair of stimulus-response tasks, reaction time is slower on trial N if a different task was performed on trial N - 1. We present a parallel distributed processing (PDP) model that simulates this effect when subjects switch between word reading and color naming in response to Stroop stimuli. Reaction time on "switch trials" can be slowed by an extended response selection process which results from (a) persisting, inappropriate states of activation and inhibition of task-controlling representations; and (b) associative learning, which allows stimuli to evoke tasks sets with which they have recently been associated (as proposed by Allport & Wylie, 2000). The model provides a good fit to a large body of empirical data, including findings which have been seen as problematic for this explanation of switch costs, and shows similar behavior when the parameters are set to random values, supporting Allport and Wylie's proposal.     

Children's reasoning about physics within and across ontological kinds

Reasoning about seven physics principles within and across ontological kinds was examined among 188 5- and 7-year-olds and 59 adults. Individuals in all age groups tended to appropriately generalize what they learned across ontological kinds. However, children also showed sensitivity to ontological kind in their projections: when learning principles with reference to people they were more likely to assume that the principles apply to another person than to an inanimate object, and when learning with reference to an inanimate object they were more likely to assume that the principles apply to another inanimate object than to a person. Five-year-olds, but not 7-year-olds, projected concepts learned about people to a greater extent than principles learned about inanimate objects, closely paralleling the findings of Carey for the biological domain (Carey, S. (1985). Conceptual change in childhood. Cambridge, MA: MIT Press). Results from a separate sample of 22 5-year-olds suggest that the primary findings cannot be explained by response perseveration. The present findings indicate that children understand physics principles that apply to both animate and inanimate objects, but distinguish between these ontological kinds.     

How do children coordinate simultaneous upper and lower extremity tasks? The development of dual motor task coordination

When performing simultaneous clapping with walking or galloping, adults adopt coupled, consistent and stable dual motor task coordination; do developmental trends in this coordination exist? In this study, we measured and compared coupling characteristics, consistency across trials and variability of phasing in 4-, 6-, 8-, and 10-year-olds (n=44) as they also performed the same dual motor task. For walk/clap, children adopted specific coupling patterns like adults by 8 years and with the same consistency by 10 years. Across age, children became less variable in clap and step movements separately and as coupled together. In the gallop/clap, children did not resemble adults in coupling patterns by 10 years but all measures were becoming more consistent across age. We discuss dual motor task coordination as a function of age and task complexity using a "dynamic" perspective within a developmental context.     

Primacy and recency effects in task analyses: Preliminary results

Performance for three independent living tasks were examined via task analyses. Given the relatively small sample size (n = 56) of individuals with intellectual and developmental disabilities, we simulated 1000 replications based upon observed results using Monte Carlo techniques. The results of the current study suggest that: (1) adaptive behavior was more related to task performance than IQ; and (2) after statistically controlling for adaptive behavior, task performance was influenced by the first step. Task performance appear to be over-estimated with the inclusion of the first step.     

领导集权度与团队成员交换：任务互依性与团队绩效压力的调节作用

从情感互动视角出发,通过三个时间节点对72个团队的问卷调查,探讨了领导集权度对团队成员交换（TMX）及团队绩效的作用机制和边界条件。结果表明：任务互依性和团队绩效压力调节了领导集权度与TMX间的关系,即任务互依性或团队绩效压力越高,领导集权度与TMX之间的负向关系越弱,反之则越强。进一步分析显示,任务互依性和团队绩效压力调节了TMX在领导集权度和团队绩效间关系的中介作用,表现为被调节的中介作用模型。     

视剥夺及视剥夺学习后Jun样蛋白在雏鸡两侧半球中不同表达的研究

该实验利用免疫组化技术,在已有实验的基础上进一步观察比较了左眼视剥夺及单眼学习后,Ｊｕｎ样蛋白在雏鸡两侧半球ＨＶ和ＬＰＯ中表达的差异。实验结果表明：１．视剥夺２、２４、４８、７２小时后观测到Ｊｕｎ样蛋白在左、右半球ＨＶ和ＬＰＯ中的表达逐渐增高,并且于视剥夺４８小时表达到达峰值。同时仅在视剥夺２小时后观测到两半球ＬＰＯ中Ｊｕｎ样蛋白的表达存在差异,在其余各视剥夺时程中两侧半球的ＬＰＯ、ＨＶ中Ｊｕｎ样蛋白的表达均无显著差异。２．视剥夺２小时和２４小时后均在学习后７０分钟组中观测到Ｊｕｎ样蛋白在左、右半球的ＨＶ和ＬＰＯ中表达的显著升高,而在视剥夺２小时学习后１０分钟只观测到左半球ＨＶ和ＬＰＯ中Ｊｕｎ样蛋白表达的显著升高,在视剥夺２４小时学习后１０分钟中仅观测到左半球ＬＰＯ中Ｊｕｎ样蛋白的显著升高。同时也仅在视剥夺２小时学习后１０分钟观测到两侧半球ＨＶ、ＬＰＯ中Ｊｕｎ样蛋白表达的显著性差异。３．无论单纯视剥夺组还是单眼学习组,各组同侧半球中ＬＰＯＪｕｎ样蛋白的表达显著高于ＨＶ的Ｊｕｎ样蛋白的表达现象在视剥夺４８小时后消失。     

Bug distribution and statistical pattern classification

A model (called the rule space model) which permits measuring cognitive skill acquisition, diagnosing cognitive errors, detecting the weaknesses and strengths of knowledge possessed by individuals was introduced earlier. This study further discusses the theoretical foundation of the model by introducing bug distribution and hypothesis testing (Bayes' decision rules for minimum errors) for classifying subjects into their most plausible latent state of knowledge. The model is illustrated with the domain of fraction arithmetic and compared with the results obtained from a conventional artificial intelligence approach.The authors would like to acknowledge Mr. Robert Baillie for developing several computer programs used for this research.This research was sponsored by the Personnel and Training Research Program, Psychological Sciences Division, Office of Naval Research.Some of the analyses presented in this report were performed on the PLATO® system. The PLATO® system is a development of the University of Illinois and PLATO® is a service mark of the Control Data Corporation.