Abstract

ROBLES, Jaime R  and  VARGAS-IRWIN, Cristina. Within-Session Analysis of the Extinction of Pavlovian Fear-Conditioning Using Robust Regression. Suma Psicol. [online]. 2010, vol.17, n.1, pp.23-24. ISSN 0121-4381.

Traditionally, the analysis of extinction data in fear conditioning experiments has involved the use of standard linear models, mostly ANOVA of between-group differences of subjects that have undergone different extinction protocols, pharmacological manipulations or some other treatment. Although some studies report individual differences in quantities such as suppression rates or freezing percentages, these differences are not included in the statistical modeling. Withinsubject response patterns are then averaged using coarse-grain time windows which can overlook these individual performance dynamics. Here we illustrate an alternative analytical procedure consisting of 2 steps: the estimation of a trend for within-session data and analysis of group differences in trend as main outcome. This procedure is tested on real fear-conditioning extinction data, comparing trend estimates via Ordinary Least Squares (OLS) and robust Least Median of Squares (LMS) regression estimates, as well as comparing between-group differences and analyzing mean freezing percentage versus LMS slopes as outcomes.

Keywords : fear conditioning extinction; within-session dynamics; robust regression; linear models; Least Median of Squares.

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