Correlative effects of psychogenetic selection: A study of the roman high and low avoidance strains of rats

A sample of 86 rats of the RHA and RLA strains, selectively bred in Rome for speed of acquisition of conditioned avoidance responses (CAR), was given the open-field test of emotionality, and re-tested for conditioning in their new environment. Both sexes were included in a balanced-order design. The standardized open-field test and a conventional shuttle-box with buzzer as the conditioned stimulus and shock as the unconditioned stimulus were used. The results show that the Roman strains do not differ in respect of open-field defecation. While the RHA strain was confirmed as superior in measures of CAR formation, it was also found to be significantly more active both in the open-field (ambulation) and in inter-trial activity during conditioning. No effects attributable either to order of test administration or the previous history of the subjects were detected, and those due to their sex merely confirmed previous findings. These results are contrasted with the findings for the Maudsley strains of reactive and non-reactive rats which differ significantly in respect of emotional elimination as a result of a similar selection procedure, but which also display a similar difference in CAR acquisition and in mature body weight.     

Olfactory discrimination of mouse strains (Mus musculus) and major histocompatibility types by humans (Homo sapiens)

A series of experiments revealed that humans can use olfaction to discriminate closely related strains of mice, differing genetically only at the major histocompatibility gene complex (H-2). In Experiment 1, subjects were asked to distinguish between the whole-body odors of live mice. In Experiments 2 and 3, the odor source was mouse fecal pellets, and in Experiments 4 and 5, the odor source was mouse urine.     

Shared maternal influences in the development of high blood pressure in the spontaneously hypertensive (SHR) and Dahl salt-sensitive (SS/Jr) rat strains.

The influence of maternal environment on the development of high blood pressure in spontaneously hypertensive (SHR) and Dahl salt-sensitive (SS/Jr) rats was examined using the technique of reciprocal cross-fostering. Previous experiments from this laboratory demonstrated that adult blood pressures of the SHR and SS/Jr strains were significantly attenuated when hypertensive-strain pups were fostered to a dam of the respective normotensive control strain during the preweaning period. In this study, SHR and SS/Jr pups were assigned to either a cross-fostered (fostered to a dam of the opposite hypertensive strain) or control-reared condition within 24 h of birth. Adult resting blood pressures were similar in control and cross-fostered SHR rats and in control and cross-fostered SS/Jr rats. Heart rates and heart, adrenal, and kidney weights were also similar in control and cross-fostered rats of each strain. However, body weights of SHR rats reared by an SS/Jr dam were somewhat lower compared to control-reared SHR rats. These data indicate that the maternal environments provided by SHR and SS/Jr mothers are similar in some way such that they permit the development and full expression of the hypertensive phenotype in both same-strain and opposite-strain pups.     

Differences between two strains of mice,selectively bred for high and low aggressiveness,in the capacity of male odors to affect aggressive behavior

The connection between a genetic disposition for aggressive behavior and the odor signal system in male mice was studied. The males belonged to two strains of mice which have been developed by selective breeding for high- (TA) and low aggressiveness (TNA). Urine from the high aggressive strain (TA), when applied to castrates, stimulated the aggressiveness of NMRI males while TA-soiled bedding suppressed their aggressiveness. In response to male odors from the low aggressive strain (TNA), the NMRI males showed quite contrasting reactions. The results provide evidences of a correlation between the hereditarily determined disposition for aggressive behavior and the odor signal system in TA- and TNA males.     

The cognitive load of physical activity in individuals with high and low tolerance to effort: An ecological paradigm to contrast stepping on the spot and stepping through space

Performing a physical activity means dealing with the challenges and difficulties occurring during the task. The more a person possesses the cognitive ability to deal with the complexity of the task, the more that person will be able to face the difficulties in activity regulation. However, no studies have been designed to investigate the cognitive dimension of physical activity. In the present study, we present an original in-task methodology that offers the means to assess the cognitive and physical load of a physical activity. Through the application of a dual task paradigm, we report in-task changes in cognitive abilities and physiological experiences in low and high tolerant individuals during the practice of one of two whole-body stepping tasks. The findings confirmed that stepping through space is a physical activity that requires more cognitive resources and is perceived as more cognitively and physically challenging than stepping on the spot. We demonstrated also that the tolerance to effort, which is a psychological factor, plays a non-negligible role in the way the activity sessions were experienced. The affective states in low tolerant individuals were always more negative than those reported by high tolerant individuals. Our findings argue for the existence of a cognitive dimension to physical activity with tolerance to effort being a moderator of individuals’ affective experience to exercise.     

Effects of some physiological and pharmacological manipulations on shock- facilitated mouse killing by onychomys leucogaster (Northern grasshopper mouse)

Onychomys leucogaster (northern grasshopper mice) were induced to kill mice with response-contingent shock, and the effects of several physiological, pharmacological, and endocrinological variables were assessed. Lesions of the septum facilitated mouse killing, while lesions of the amygdala abolished spontaneous mouse killing and delayed shock-facilitated killing. Chlorpromazine (2.5–5 mg/kg) and chlordiazepoxide (5–10 mg/kg) facilitated mouse killing on postdrug trials but did not affect killing when the animals were drugged. Adrenalectomy, castration, and castration adrenalectomy did not alter the frequency of kill nor were sex-related differences in killing noted. These results were compared to those found by others studying the effects of lesions and drugs on mouse killing by rats.     

Eye movements of prereaders to pseudowords containing letters of high and low confusability

Children were required to make same-different judgments about matched and unmatched pseudoword pairs containing middle letters of either high confusability (e.g.. ZPR.W or low confusability (e.g., EROI). Differential eye-movement patterns were observed between matched and unmatched low-confusion pairs. This finding would be predicted from a features analysis of the visual characteristics of the letters of the pseudowords. Low-confusion pseudowords contain more different visual features than high-confusion pseudowords. Therefore, in making a matching judgment. low-confusion pairs should require more eye movements; however, detection of a mismatch should be facilitated due to the greater availability of distinctive features.     

Field response of acromyrmex crassispinus (forel) to aggression by atta sexdens (linn.) and predation by labidus praedator (fr. smith) (hymenoptera: Formicidae)

Aggression between colonies of the leaf-cutting ants, Acromyrmex crassispinus and Atta sexdens, was followed in the field. A. sexdens dominated the A. crassispinus nest, but did not overcome it. The A. crassispinus nest was subsequently raided by Labidus praedator, which took larvae and pupae without killing the colony. Aggression between the leaf-cutting ant colonies lasted 17 days. Microgyne production and nest displacement in the attacked A. crassispinus colony may be atrributed to stress.     

Deciding between accounts of the selection task: A reply to Oaksford (2002)

In this paper we report on our attempts to fit the optimal data selection (ODS) model (Oaksford & Chater, 1994; Oaksford, Chater, & Larkin, 2000) to the selection task data reported in Feeney and Handley (2000) and Handley, Feeney, and Harper (2002). Although Oaksford (2002b) reports good fits to the data described in Feeney and Handley (2000), the model does not adequately capture the data described in Handley et al. (2002). Furthermore, across all six of the experiments modelled here, the ODS model does not predict participants' behaviour at the level of selection rates for individual cards. Finally, when people's probability estimates are used in the modelling exercise, the model adequately captures only 1 out of 18 conditions described in Handley et al. We discuss the implications of these results for models of the selection task and claim that they support deductive, rather than probabilistic, accounts of the task.     

Personality differences among female student teachers of relatively high and low mental ability.

30 Ss scoring between 125 and 139 and 30 (out of 100) from 79 to 112 on the California Short-form Test of Mental Maturity were significantly different on the 16 PF only on Factors B and H (p = .05) and not on the California F scale. Significant comparisons appeared to be chance effects.     

Implicit activation of alcohol concepts by negative affective cues distinguishes between problem drinkers with high and low psychiatric distress.

This study tested the hypothesis that negative affective (NEG) cues activate alcohol concepts more strongly in problem drinkers with high rather than low psychiatric distress (PD) and that a parallel difference applies to activation of NEG concepts by alcohol cues. A lexical decision task assessed memory activation in 36 problem drinkers with high vs. low scores on the Symptom Checklist-90. High PD drinkers displayed activation in each condition; low PD drinkers displayed inhibition. Activation of alcohol concepts by NEG cues correlated with intensity of PD, bias to drink in NEG states, and confidence to avoid drinking in these states. Results corroborate in vivo cue reactivity studies and indicate a functional difference between problem drinkers with high and low PD.     

Control by action representation and input selection (CARIS): a theoretical framework for task switching

Control by action representation and input selection (CARIS) is a modeling framework for task-switching experiments, which considers action-related effects as critical constraints. It assumes that control operates by choosing control parameter values, representing input selection and action representation. Competing CARIS models differ in whether (a) control parameters are determined by current instructions or represent a perseveration, (b) current instructions apply to the input selection and/or to action representation. According to the chosen model (a) task execution results in a default bias in favor of the executed task thus creating perseverative tendencies; (b) control counteracts these tendencies by applying a transient momentary bias whose locus (input selection or action representation) changes as a function of task preparation time; (c) this happens because the task-cue (e.g., SHAPE) initially attracts attention to the immediately available cue-information (e.g., target shape) and then attracts it to inferred or retrieved information (e.g., "circle" is related to the right key press).