Intruding male red swamp crayfish,Procambarus clarkii,immediately dominate members of established communities of smaller,mixed-sex conspecifics

The effects of competing asymmetries (intruder size advantage vs. prior residence) on dominance relationships were investigated in a laboratory setting. Sexually mature (Form I) male red swamp crayfish, 25%-27% larger than the average member of several mixedsex communities of 20-25 sexually mature conspecifics, individually intruded upon these communities on successive days. Each community was invaded once a day, with each of these large intruders invading every community once during the experiment. Five days after the last large intruder invasion, novel intruder group males, approximately the same size as the average community member, individually invaded the same communities, all communities being invaded once during a single day of testing. These novel intruders were used to differentiate the effects of intruder size from those effects of being put into a novel environment. During each intrusion, the frequencies of dominance, submission, aggressive standoffs, and nonaggressive interactions between the intruder and members of the community were recorded. The large intruders on each day immediately and virtually completely dominated all encountered community members, and the large intruders were significantly more dominant than the novel, smaller-sized intruders. The size advantage of the large intruders overwhelmed prior residence in influencing dominance outcomes, even in these well established communities. © 1995 Wiley-Liss, Inc.     

Tracking mouse movement in feature inference: Category labels are different from feature labels

In this article, we examine the role of category labels in inductive inference. Some leading research has suggested that information about category membership works just like any other feature in categorical inductions, whereas other research has proposed that the influence of category membership on induction goes beyond that of other features. To investigate these claims further, we developed an online measure of judgments that is akin to eyetracking. The judgment results and the mouse-tracking data jointly support the view that category labels do affect inductive inferences in a way distinct from that for feature information. When arbitrary labels conveyed category membership information, participants viewed these labels more often and earlier in a trial, in comparison with cases in which the same labels conveyed non-membership information. Our results suggest that category membership information works like a guide for inference. An ecological rationale for this induction strategy is also discussed.     

Overcoming intuition: metacognitive difficulty activates analytic reasoning

Humans appear to reason using two processing styles: System 1 processes that are quick, intuitive, and effortless and System 2 processes that are slow, analytical, and deliberate that occasionally correct the output of System 1. Four experiments suggest that System 2 processes are activated by metacognitive experiences of difficulty or disfluency during the process of reasoning. Incidental experiences of difficulty or disfluency--receiving information in a degraded font (Experiments 1 and 4), in difficult-to-read lettering (Experiment 2), or while furrowing one's brow (Experiment 3)--reduced the impact of heuristics and defaults in judgment (Experiments 1 and 3), reduced reliance on peripheral cues in persuasion (Experiment 2), and improved syllogistic reasoning (Experiment 4). Metacognitive experiences of difficulty or disfluency appear to serve as an alarm that activates analytic forms of reasoning that assess and sometimes correct the output of more intuitive forms of reasoning.     

Tracking the continuity of language comprehension: computer mouse trajectories suggest parallel syntactic processing

Although several theories of online syntactic processing assume the parallel activation of multiple syntactic representations, evidence supporting simultaneous activation has been inconclusive. Here, the continuous and non-ballistic properties of computer mouse movements are exploited, by recording their streaming x, y coordinates to procure evidence regarding parallel versus serial processing. Participants heard structurally ambiguous sentences while viewing scenes with properties either supporting or not supporting the difficult modifier interpretation. The curvatures of the elicited trajectories revealed both an effect of visual context and graded competition between simultaneously active syntactic representations. The results are discussed in the context of 3 major groups of theories within the domain of sentence processing.     

Assessment of age-related changes in inhibition and binding using eye movement monitoring

Age-related memory deficits may result from attending to too much information (inhibition deficit) and/or storing too little information (binding deficit). The present study evaluated the inhibition and binding accounts by exploiting a situation in which deficits of inhibition should benefit relational memory binding. Older adults directed more viewing toward abrupt onsets in scenes compared with younger adults under instructions to ignore any such onsets, providing evidence for age-related inhibitory deficits, which were ameliorated with additional practice. Subsequently, objects that served as abrupt onsets underwent changes in their spatial relations. Despite successful inhibition of the onsets, eye movements of younger adults were attracted to manipulated objects. In contrast, the eye movements of older adults, who directed more viewing to the late onsets compared with younger adults, were not attracted toward manipulated regions. Similar differences between younger and older adults in viewing of manipulated regions were observed under free viewing conditions. These findings provide evidence for concurrent inhibition and binding deficits in older adults and demonstrate that age-related declines in inhibitory processing do not lead to enhanced relational memory for extraneous information.     

Executive function in CHARGE syndrome.

This study addressed the presence of executive dysfunction in children with CHARGE syndrome, a genetic disorder with multiple physical anomalies and severe challenging behaviors. Ninety-eight children were included in the study. More than half received clinically significant scores on the Behavior Rating Inventory of Executive Function (BRIEF; Gioia et al., 2000) scales of Shift, Monitor, and the Behavioral Regulation Index, with additional high scores on Inhibit and the Global Executive Composite. Associations were found with the age the child first walked, scores on the Autism Behavior Checklist (ABC; Krug et al., 1993), and being classified as deafblind. Difficulties with making transitions and flexible problem solving, monitoring their work and their effect on others, and acting on impulse, may be related to the behavioral difficulties exhibited by children with CHARGE. Interventions targeting improved self-regulation may help to manage this challenging behavior.     

Anxiety sensitivity and intolerance of uncertainty: requisites of the fundamental fears?

Fears related to anxiety sensitivity (AS)-illness/injury sensitivity, fear of negative evaluation, and fear of pain-may have important theoretical associations with intolerance of uncertainty (IU). In separate investigations, AS and IU have been independently related to the same anxiety-related psychopathology. AS and IU seem to share a basis in fearing unknown, potentially harmful consequences; however, their inter-relationship remains uncertain. IU regarding a specific stimulus, a physical sensation for example, may result in a variety of interpretations and responses, including the catastrophic appraisals that characterize AS. The association between AS and IU was examined in a sample of 293 undergraduates. Results of confirmatory factor and correlation analyses suggest the two constructs are related, but nonetheless independent. It appears that IU may be a required component of catastrophic misappraisals while being an important construct related to fear and anxiety in its own right. Future research directions and potential applications are discussed.     

Suicide schema in schizophrenia: the effect of emotional reactivity, negative symptoms and schema elaboration

Suicide risk is thought to increase with a greater potential for activation of suicide-related schemas. Suicide schemas are less likely to be activated with reductions of emotional range associated with certain negative symptoms of schizophrenia. The study tested whether suicide risk would increase in patients with recent onset schizophrenia with increased potential for suicide schema activation as indicated by lower levels of specific negative symptoms that reflected emotional reactivity, namely emotional withdrawal and blunted affect. A logistic regression analysis of baseline data of 278 recent onset schizophrenic patients with a measure of suicide behaviour as the dependent variable and negative symptoms, delusions, hallucinations, depression, gender, episode, ethnicity, education, age, duration of untreated psychosis and substance use as independent variables was carried out. Emotional withdrawal, but not blunted affect was significant and negatively associated, and depression positively associated with suicide behaviour. There was evidence to indicate that restricted emotions are associated with reduced suicide risk as predicted.