In this article we describe some of the experimental software we have developed for the study of associative human learning and memory. All these programs have the appearance of very simple video games. Some of them use the participants ’ behavioral responses to certain stimuli during the game as a dependent variable for measuring their learning of the target cue-outcome associations. Some others explicitly ask participants to rate the degree of relationship they perceive between the cues and the outcomes. These programs are implemented in Web pages using JavaScript, which allows their use both in traditional laboratory experiments as well as in Internet-based experiments. The psychology of learning is a research area that has usually been investigated with nonhuman animals and in which, traditionally, there existed too many procedural and ethical problems to conduct experiments with humans. However, human learning is today a flourishing research area in which many interesting effects are being reported around the world (see, e.g., De Houwer &

Most theoretical accounts of backward blocking place heavy stress on the necessity of the target cue having been trained in compound with the competing cue to produce a decrement in responding. Yet, other evidence suggests that a similar reduction in responding to the target cue can be observed when the outcome is later paired with a novel cue never trained in compound with the target cue (interference between cues trained apart). The present experiment shows that pairing another nonassociated cue with the same outcome may be sufficient to produce a decremental effect on the target cue, but the presence of a within-compound association between the target and the competing cue adds to this effect. Thus, both interference between cues trained apart and within-compound associations independently contribute to backward blocking.

Backward blocking (BB) and interference between cues (IbC) are cue competition effects produced by very similar manipulations. In a standard BB design both effects might occur simultaneously, which implies a potential problem to study BB. In the present study with humans, the magnitude of both effects was compared using a non causal scenario and a within subjects design. Previous studies have made this comparison using learning tasks framed within causal scenarios. This posits a limit to generalizing their findings to non-causal learning situations because there is ample evidence showing that participants engage in causal reasoning when tasks are causally framed. The results obtained showed BB and IbC effects of the same magnitude in a non causal framed task. This highlights the methodological need for an IbC control in BB experiments. Backward Blocking 3

Abstract not found

Retroactive interference between cues trained apart has been regarded as an effect that occurs because the target and interfering associations share a common outcome. Although this view is consistent with evidence in the verbal learning tradition (Underwood, 1966) and, more recently, in predictive learning with humans (Pineño & Matute, 2000), little research has been conducted to ascertain whether the occurrence of this effect critically depends on the target and interfering associations sharing an identical outcome. The present experiment examined, in predictive learning with humans, retroactive interference between cues trained apart as a function of the similarity of the outcome paired with the cues. Interference was found to be stronger when the cues were paired with the same outcome than when they were paired with either similar or different outcomes.

Backward blocking (BB) and interference between cues (IbC) are cue competition effects produced by very similar manipulations. In a standard BB design, both effects might occur simultaneously, which implies a potential problem for studying BB. In the present study with humans, the magnitude of both effects was compared using a non-causal scenario and a within-subjects design. Previous studies have made this comparison using learning tasks framed within causal scenarios. This posits a limit to generalizing their findings to non-causal learning situations because there is ample evidence showing that participants engage in causal reasoning when tasks are causally framed. The results obtained showed BB and IbC effects of the same magnitude in a non– causally-framed task. This highlights the methodological need for an IbC control in BB experiments.