Perceptual learning transfer in an appetitive Pavlovian task

Abstract

In two experiments, rats were given intermixed or blocked preexposure to two similar compound stimuli, AX and BX. Following preexposure, conditioning trials took place in which AX (Experiment 1) or a novel compound stimulus NX (Experiment 2) was paired with a food-unconditioned stimulus in an appetitive Pavlovian preparation. Animals that were given alternated preexposure showed lower generalization from AX to BX (Experiment 1) and from NX to a new compound, ZX (Experiment 2), than animals that were given blocked preexposure, a perceptual learning and a perceptual learning transfer effect, respectively.

Mechanisms of perceptual learning: Prolonged intermixed preexposure reduces the effectiveness of the unique and the common elements.

“…BX, BX). Doubling the amount of preexposure (20 preexposure trials to each compound instead of 10) used in previous studies using the same appetitive conditioning procedure (i.e., Artigas & Prados, 2017;Mondragón & Murphy, 2010), Experiment 1 showed the This document is copyrighted by the American Psychological Association or one of its allied publishers.…”

“…condition (see Artigas & Prados, 2017, for an identical experiment with a generalization test; also Mondragón & Murphy, 2010), they seem to be insufficient to differentially affect the salience of the unique and common elements in the two preexposure procedures, intermixed and blocked. As mentioned above, it could be the case that the modified salience of the unique and common elements affect the ease at which animals discriminate between the compound stimuli AX and BX, but it is not sufficient to guarantee an effect on the acquisition of associative strength when used as a CS in Pavlovian conditioning.…”

“…Independent of the nature of the processes triggered by preexposure, the effect of these processes would be gradual and would require some time to differentially alter the salience of the unique and common elements in the intermixed and blocked preexposure conditions. Assuming the salience or effectiveness of the common element X is differentially affected in the different preexposure procedures, a more reliable effect could emerge extending the amount of preexposure used in previous studies using auditory compound stimuli and an appetitive task (Artigas & Prados, 2017;Mondragón & Murphy, 2010). It could be the case that with the level of preexposure used in these experiments, although the modified salience of the common element affects the ease at which animals discriminate between the compound stimuli AX and BX, it is not sufficient to guarantee an effect on the acquisition of associative strength when the common element X is used as a CS in Pavlovian conditioning.…”

Preexposure along a continuum: Differentiation and association.

“…Although a reduction in the effective salience of common features has been proposed as one mechanism of perceptual learning, preexposure to the common features (or midpoint) alone is not the most commonly used, nor always the most effective, method for producing a perceptual learning effect. Perceptual learning has been found after preexposure to the discriminative stimuli themselves in a number of preparations including visual discrimination learning (e.g., Gibson & Walk, 1956), maze learning (e.g., Trobalon, Sansa, Chamizo, & Mackintos, 1991), navigation in a water maze (e.g., Prados, Chamizo, & Mackintosh, 1999), conditioned flavor aversion (e.g., Mackintosh et al, 1991; Rodríguez, Blair, & Hall, 2008; Symonds & Hall, 1995), texture discrimination learning (Montuori & Honey, 2016), and auditory discrimination learning (Artigas & Prados, 2017; Mondragón & Murphy, 2010). Indeed, alternating preexposure has, on occasion, been found to result in the largest reduction in generalization between two stimuli (e.g., Dwyer, Hodder, & Honey, 2004; Honey et al, 1994; Mundy et al, 2007; Symonds & Hall, 1995).…”

“…The purpose of the experiments reported here was to explore the generality of Montuori and Honey's findings for a different perceptual dimension, auditory frequency. Although Mondragón and Murphy (2010; see also Artigas & Prados, 2017) have previously reported a perceptual learning effect using tones that differed in frequency, they presented them in compound with the common feature of white noise. Here we used pure tones or clickers that differed only in frequency which allowed us to explore the effects of pre-exposure to the midpoint between discriminative stimuli as well as pre-exposure to the stimuli themselves.…”