A Rescorla-Wagner Drift-Diffusion Model of Conditioning and Timing

Computational models of classical conditioning have made significant contributions to the theoretic understanding of associative learning, yet they still struggle when the temporal aspects of conditioning are taken into account. Interval timing models have contributed a rich variety of time representations and provided accurate predictions for the timing of responses, but they usually have little to say about associative learning. In this article we present a unified model of conditioning and timing that is based on the influential Rescorla-Wagner conditioning model and the more recently developed Timing Drift-Diffusion model. We test the model by simulating 10 experimental phenomena and show that it can provide an adequate account for 8, and a partial account for the other 2. We argue that the model can account for more phenomena in the chosen set than these other similar in scope models: CSC-TD, MS-TD, Learning to Time and Modular Theory. A comparison and analysis of the mechanisms in these models is provided, with a focus on the types of time representation and associative learning rule used

Motivational Interviewing as Evidence-Based Practice? An Example from Sexual Risk Reduction Interventions Targeting Adolescents and Young Adults

This paper critically examines sexual risk reduction interventions, more specifically how they are evaluated and the implications that this has for sexual health policy. The focus is on motivational interviewing (MI) interventions which aim to promote protective behaviors related to sexual risk on the part of young people. MI has become increasingly popular, largely due to it being a highly flexible counseling approach that may, with adequate staff training, and fidelity in implementation, be tailored to many different settings (e.g., health care, schools and in community work). Following a scoping review that comprised 34 papers, of which 29 were unique studies, the range and type of existing research were examined. The results show a wide range of study designs and evaluation procedures, MI conceptualizations, modes of MI delivery, and the particular sub-populations of youth and sexual risk behaviors targeted. While this makes it difficult to draw any generalized conclusions about “what works” in prevention, it provides important insights about the complexity of sexual risk behavior as well as complex behavioral treatment approaches like MI. We therefore problematize the political drive to implement evidence-based methods without adequate resource allocation and contextual adaptation

CHARACTERIZATION OF PARASITE ANTIGENS FROM HUMAN HYDATID CYST FLUID BY SDS-PAGE AND IEF

Combining high resolution power of SDS-PAGE and IEF with the specific immunological recognition of a human antiserum directed against Echinococcus granulosus antigens, we could identify, in 4 hydatid cystic fluids of human origin, 4 antigens with a molecular weight in the range 32-13 KD, and an antigen of 200 KD which, in reducing conditions, gave 2 bands of 67 and 52 KD. In addition, mainly in one of the cystic fluids, there were at least another 4 specific non-reducible bands with a molecular weight ranging from 80 to 40 KD. Specific parasite antigens, which constitute not more than 3% of total protein content of the cystic fluid, migrate, in isoelectric focusing, from a pH of less than 5 to more than 8. © 1985 Springer-Verlag