A novel continuous inhibitory-control task: variation in individual performance by young pheasants (<Emphasis Type="Italic">Phasianus colchicus</Emphasis>)

Inhibitory control enables subjects to quickly react to unexpectedly changing external demands. We assessed the ability of young (8 weeks old) pheasants Phasianus colchicus to exert inhibitory control in a novel response-inhibition task that required subjects to adjust their movement in space in pursuit of a reward across changing target locations. The difference in latencies between trials in which the target location did and did not change, the distance travelled towards the initially indicated location after a change occurred, and the change-signal reaction time provided a consistent measure that could be indicative of a pheasant’s inhibitory control. Between individuals, there was a great variability in these measures; these differences were not correlated with motivation either to access the reward or participate in the test. However, individuals that were slower to reach rewards in trials when the target did not change exhibited evidence of stronger inhibitory control, as did males and small individuals. This novel test paradigm offers a potential assay of inhibitory control that utilises a natural feature of an animal’s behavioural repertoire, likely common to a wide range of species, specifically their ability to rapidly alter their trajectory when reward locations switch.     

Social feedback interferes with implicit rule learning: Evidence from event-related brain potentials

The human brain can learn contingencies built into stimulus sequences unconsciously. The quality of such implicit learning has been connected to stimulus social relevance, but results so far are inconsistent. We engaged participants in an implicit-intentional learning task in which they learned to discriminate between legal and illegal card triads on the sole basis of feedback provided within a staircase procedure. Half of the participants received feedback from pictures of faces with a happy or sad expression (social group) and the other half based on traffic light icons (symbolic group). We hypothesised that feedback from faces would have a greater impact on learning than that from traffic lights. Although performance during learning did not differ between groups, the feedback error-related negativity (fERN) was delayed by ~20 ms for social relative to symbolic feedback, and the P3b modulation elicited by infrequent legal card triads within a stream of illegal ones during the test phase was significantly larger in the symbolic than the social feedback group. Furthermore, the P3b mean amplitude recorded at test negatively correlated with the latency of the fERN recorded during learning. These results counterintuitively suggest that, relative to symbolic feedback, socially salient feedback interferes with implicit learning.     

The inhibitory control of pheasants (Phasianus colchicus) weakens when previously learned environmental information becomes unpredictable

Animal Cognition - Inhibitory control (IC) is the ability to intentionally restrain initial, ineffective responses to a stimulus and instead exhibit an alternative behaviour that is not pre-potent...     

Conditional estimation of exponential random graph models from snowball sampling designs

A complete survey of a network in a large population may be prohibitively difficult and costly. So it is important to estimate models for networks using data from various network sampling designs, such as link-tracing designs. We focus here on snowball sampling designs, designs in which the members of an initial sample of network members are asked to nominate their network partners, their network partners are then traced and asked to nominate their network partners, and so on. We assume an exponential random graph model (ERGM) of a particular parametric form and outline a conditional maximum likelihood estimation procedure for obtaining estimates of ERGM parameters. This procedure is intended to complement the likelihood approach developed by  Handcock and Gile (2010) by providing a practical means of estimation when the size of the complete network is unknown and/or the complete network is very large. We report the outcome of a simulation study with a known model designed to assess the impact of initial sample size, population size, and number of sampling waves on properties of the estimates. We conclude with a discussion of the potential applications and further developments of the approach.     

Information search patterns for gift purchases: a cross‐national examination of gender differences

This exploratory study examines the underlying determinants as well as the dimensionality of in‐store information searches for a Christmas clothing gift, focusing specifically on the differential effect of gender on information acquisition. A self‐administered survey, containing personality, situational and standard demographic measures, was administered to actual consumers in three Western countries, shortly after the Christmas season. Confirmatory factor analysis verified that in‐store information is indeed a multidimensional construct, composed of three distinct factors: macro information search, micro information search and salesperson help. Consistent with expectations, compared to males, females tended to acquire macro and micro information to a greater extent; males were more apt to seek the assistance of store sales personnel than females. This pattern was generally robust across the three countries. Other observed gender and/or country‐sample differences are discussed. Copyright © 2002 Henry Stewart Publications Ltd.     

Network models for social influence processes

This paper generalizes thep* class of models for social network data to predict individual-level attributes from network ties. Thep* model for social networks permits the modeling of social relationships in terms of particular local relational or network configurations. In this paper we present methods for modeling attribute measures in terms of network ties, and so constructp* models for the patterns of social influence within a network. Attribute variables are included in a directed dependence graph and the Hammersley-Clifford theorem is employed to derive probability models whose parameters can be estimated using maximum pseudo-likelihood. The models are compared to existing network effects models. They can be interpreted in terms of public or private social influence phenomena within groups. The models are illustrated by an empirical example involving a training course, with trainees' reactions to aspects of the course found to relate to those of their network partners.This research was supported by grants from the Australian Research Council. The authors would like to acknowledge the help of Stanley Wasserman, Janice Langan-Fox and Larry Hubert, and would like to thank four anonymous reviewers for their helpful comments. Earlier versions of this article were presented at the North American Conference of the Psychometric Society, Lawrence, Kansas, June, 1999, and at the Australasian Mathematical Psychology Conference, Brisbane, Australia, December 1999.     

Processing of facial expressions of negative emotion in alexithymia: the influence of temporal constraint

Alexithymia, a characteristic involving a limited affective vocabulary appears to involve three components: difficulty identifying feelings, difficulty describing feelings, and externally oriented thinking. There is evidence that alexithymic characteristics are associated with differences in emotion information-processing. We examined the role of temporal factors in alexithymic emotion-processing deficits, taking into account the confound between alexithymic characteristics and positive and negative affectivity. One hundred forty-six participants completed the 20-item Toronto Alexithymia Scale and the Positive and Negative Affect Schedule. In a signal-detection paradigm, participants judged facial expressions depicting neutral or negative emotions under slow and rapid presentation conditions. The alexithymia component of difficulty in describing feelings was inversely related to the ability to detect expressions of negative emotion in the speeded condition. This relationship was independent of positive and negative affectivity. Alexithymic components positive and negative affectivity were unrelated to response bias. The results emphasize the influence of difficulty describing feelings within the alexithymia construct and its difference from positive and negative affectivity. They suggest that an alexithymic deficit in describing feelings is associated with a deficit in processing negative emotions that is most apparent when processing capacity is challenged. Theoretical and methodological implications are discussed.     

Connecting neurosis and psychosis: the direct influence of emotion on delusions and hallucinations

Diagnostic classification systems contain a core divide between neurosis and psychosis, leading to their separate study and treatment. The basis for the separation of the disorders is outlined and reassessed. It is argued that the empirical evidence does not support such a sharp distinction between neurosis and psychosis. The frequent occurrence of emotional disorder prior to and accompanying psychosis indicates that neurosis contributes to the development of the positive symptoms of psychosis. Psychological theories and experimental evidence concerning the influence of emotion on the content and form of delusions and hallucinations are therefore reviewed. It is argued that in many cases delusions are a direct representation of emotional concerns, and that emotion contributes to delusion formation and maintenance. The content of hallucinations less often directly expresses the emotional concerns of the individual, but emotion can trigger and contribute to the maintenance of hallucinatory phenomena, although how this occurs is not well understood. It is concluded that study needs to be made of the interaction between psychotic and neurotic processes in the development of delusions and hallucinations, and that neurotic and psychotic disorders may have common maintenance processes.