State-dependent and odor-mediated anemotactic responses of a micro-arthropod on a novel type of locomotion compensator

A novel type of locomotion compensator was designed and tested for its use in orientation behavior experiments with a predatory mite. In this apparatus, displacements of the test animal in the two-dimensional plane are recorded using video equipment and a servosphere that keeps the animal in focus. Thex andy displacements are registeredusing two rotation encoders and are compensated using a pair of servo-motors, in such a way that the animal is always positioned on top of the sphere, yet moves freely. Well-fed and starved predators were tested for their responses to (1) still air, (2) a stimulus-free air flow, (3) an air flow with odors from uninfested Lima bean leaves, and (4) an air flow with odors from Lima bean leaves infested by plant-feeding mites, the prey of the predatory mites. Anemotactic responses of adultPhytoseivlus persimilis females were feeding state dependent. Well-fed predators moved downwind under Treatments 1–3 but moved neither up-nor downwind in the presence of odors from infested plants (Treatment 4). Starved predators moved upwind under all treatments. These results are in agreement with those of earlier studies in a wind tunnel, and therefore, the new type of locomotion compensator (LC-100) offers an excellent method for studying the orientation behavior of micro-arthropods.     

Children's nighttime fears: parent-child ratings of frequency, content, origins, coping behaviors and severity

The present study investigated nighttime fears in normal school children aged 4 to 12 yr (N=176). Children and their parents were interviewed about the frequency, content, origins, coping behaviors and severity of children's nighttime fears. Results showed that 73.3% of the children reported nighttime fears, indicating that these fears are quite prevalent. Inspection of the developmental course of nighttime fears revealed that these fears are common among 4- to 6-year-olds, become even more frequent in 7- to 9-year-olds and then remain relatively stable in 10- to 12-year-olds. Inspection of the origins of nighttime fears revealed that most of the children (i.e., almost 80%) attributed their fear to negative information; conditioning and modeling were endorsed less frequently (25.6% and 13.2%, respectively). A substantial percentage of the children (24.0%) indicated that learning experiences had not played a role in the acquisition of their nighttime fears. Children reported a variety of coping strategies in order to deal with their nighttime fears and generally rated these strategies as helpful in reducing anxiety. Furthermore, children's nighttime fears were associated with moderate levels of anxiety. Moreover, in about 10% of the children, nighttime fears were related to one or more DSM-III-R anxiety disorders. Finally, parental reports of children's nighttime fears substantially deviated from children's reports. Most importantly, parents provided a marked underestimation of the frequency of nighttime fears, at least as reported by their children.     

Changes in executive control across the life span: examination of task-switching performance

A study was conducted to examine changes in executive control processes over the life span. More specifically, changes in processes responsible for preparation and interference control that underlie the ability to flexibly alternate between two different tasks were examined. Individuals (N = 152) ranging in age from 7 to 82 years participated in the study. A U-shaped function was obtained for switch costs (i.e., the time required to switch between tasks compared with a repeated-task baseline), with larger costs found for young children and older adults. Switch costs were reduced with practice, particularly for children. All age groups benefited from increased preparation time, with larger benefits observed for children and older adults. Adults benefited to a greater extent than children when the interval between the response to one task and the cue indicating which task to perform next was lengthened, which suggested faster decay of interference from the old task set for adults than for children. A series of hierarchical analyses indicated that the age-related variance in task-switching performance is independent, at least in part, from the age-related variance in other cognitive processes such as perceptual speed and working memory. The results are discussed in terms of the development and decline of executive control processes across the life span.     

Unconditionally Selective Dependence of Random Variables on External Factors

What is the meaning of saying that random variables {X(1), em leader, X(n)} (such as aptitude scores or hypothetical response time components), not necessarily stochastically independent, are selectively influenced respectively by subsets {Gamma(1), em leader, Gamma(n)} of a factor set Phi upon which the joint distribution of {X(1), em leader, X(n)} is known to depend? One possible meaning of this statement, termed conditionally selective influence, is completely characterized in Dzhafarov (1999, Journal of Mathematical Psychology, 43, 123-157). The present paper focuses on another meaning, termed unconditionally selective influence. It occurs when two requirements are met. First, for i=1, em leader, n, the factor subset Gamma(i) is the set of all factors that effectively change the marginal distribution of X(i). Second, if {X(1), em leader, X(n)} are transformed so that all marginal distributions become the same (e.g., standard uniform or standard normal), the transformed variables are representable as well-behaved functions of the corresponding factor subsets {Gamma(1), em leader, Gamma(n)} and of some common set of sources of randomness whose distribution does not depend on any factors. Under the constraint that the factor subsets {Gamma(1), em leader, Gamma(n)} are disjoint, this paper establishes the necessary and sufficient structure of the joint distribution of {X(1), em leader, X(n)} under which they are unconditionally selectively influenced by {Gamma(1), em leader, Gamma(n)}. The unconditionally selective influence has two desirable properties, uniqueness and nestedness: {X(1), em leader, X(n)} cannot be influenced selectively by more than one partition {Gamma(1), em leader, Gamma(n)} of the factor set Phi, and the components of any subvector of {X(1), em leader, X(n)} are selectively influenced by the components of the corresponding subpartition of {Gamma(1), em leader, Gamma(n)}. Copyright 2001 Academic Press.     

Toddlers' use of metric information and landmarks to reorient

Mobile organisms can keep track of spatial location (both their own location and that of objects in the environment) using either an external referent system or one centered on the self and updated by information about movement through space. When the latter system is disabled (e.g., by rapid turning), aspects of the external world must be used to reestablish orientation. Recently, it has been claimed that, both for rats and for human toddlers, reorientation is achieved using a geometric module that accepts only information about the metric properties of the environment (C. R. Gallistel, 1990; L. Hermer & E. S. Spelke, 1994, 1996). In a series of experiments, this paper confirms that geometric information is used for reorientation by young children, but gives reason to doubt that the use of this information is achieved using a module impenetrable to nongeometric information.     

Conceptualization of perceptual attributes: a special case for color?

Young children experience difficulties establishing conceptual representations of color compared with everyday objects. We argue that comparing the development of color cognition to that of familiar objects is inappropriate since color is a perceptual attribute that can be abstracted from an object and by itself lacks functional significance. Instead, we compared the recognition, perceptual saliency, and naming of color to that of three other perceptual object attributes (motion, form, and size) in 47 children aged 2 to 5 years as a function of language age. Results revealed that, although color was perceptually salient relative to the other visual attributes, no selective impairment to color cognition (recognition and naming) was found relative to the three other visual attributes tested. Thus, when the appropriate comparisons are made, we find no special delay in the development of color conceptualization. Furthermore, the striking disparity between perceptual saliency and cognition of color in our youngest age groups suggests that perceptual saliency has little influence on the conceptual development of color.     

The predictive strength of personal constructs versus conventional constructs: self-image disparity and neuroticism

Idiographic personal construct (PC) measures of self-image disparity were hypothesized to be stronger than nonidiographic conventional construct (CC) measures in predicting neuroticism. Ninety-six college students completed PC and CC measures of real self, ideal self, social self, and ideal social self; the NEO Five-Factor Inventory; and the Marlowe-Crowne Social Desirability Scale. Content analysis showed that individuals' PC measures were unique. The disparity between real self and ideal self and the disparity between social self and ideal social self were computed for PC and CC; test-retest reliabilities were .76 to .81. Results of simultaneous multiple regression analyses supported the hypothesis. Also, the two-variable PC self-image disparity scores were stronger than one-variable PC esteem scores in predicting neuroticism. Implications were discussed for research method, self-concept theory, personal construct theory, neuroticism, and psychotherapy.     

Neuroticism and social comparison orientation as moderators of affective responses to social comparison at work

In a study among 72 nurses, the affective consequences of social comparison were examined and related to neuroticism (N) and to social comparison orientation (SCO). Participants were confronted with a bogus interview with an upward versus a downward comparison target. Positive affect and identification were higher, and negative affect was lower, in the upward than in the downward comparison condition. Independent of their SCO, the higher individuals were in N, the less they identified with the upward comparison target, the more they identified with the downward comparison target, and the less positive affect they showed following confrontation with the upward comparison target. In contrast, independent of their level of N, the higher individuals were in SCO, the more negative affect they showed following confrontation with the downward comparison target. The effects on negative affect stayed the same when controlling for positive affect, and the effects on positive affect stayed the same when controlling for negative affect. These effects were also obtained when perceived direction was used as a predictor instead of the experimentally manipulated direction. It is concluded that, although N and SCO are correlated, these variables seem to have independent and distinct effects upon the responses to social comparison information.     

Development of lower extremity kinetics for balance control in infants and young children

Developmental changes in the kinematics and kinetics underlying balance control were studied in 61 children, 9 months to 10 years of age. The children were classified according to developmental milestones as standers; new, intermediate, and advanced walkers; runners-jumpers; hoppers; gallopers; and skippers. The children experienced support-surface translations of varying size and speed. Children with greater locomotor experience withstood larger balance threats without collapsing or stepping. Analyses of scaled trials (perturbations normalized in size to foot length and center of gravity height) revealed that improvement in balance was not related to initial configuration parameters surrounding the task (degree of crouch or lean). Children with advanced locomotor skills had faster recovery times and relatively larger muscle torques than children with less experience. Relative torque-time histories of the more experienced children began to match the adult response to similar perturbations. With increased experience and changing muscle torque regulatory abilities, balance skills became more robust.     

Effects of an early intervention group program for anxious and depressed adolescents: a pilot study

The Resourceful Adolescent Program is an early intervention program designed to enhance psychological resilience in adolescents with emotional problems. Eight adolescents with high anxious and/or depressive symptoms were treated with this 11-session group program. Treatment effects were examined by means of self-report questionnaires of anxiety, depression, and self-efficacy. Pre- and postintervention data showed reductions in anxiety and depression scores and a concomitant increase in adolescents' self-efficacy.