Leyre Castro

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It is said that "absence makes the heart grow fonder." But, when and why does an absent event become salient to the heart or to the brain? An absent event may become salient when its nonoccurrence is surprising. Van Hamme and Wasserman (1994) found that a nonpresented but expected stimulus can actually change its associative status-and in the opposite(More)
The authors explored whether pigeons can learn to discriminate simultaneously presented arrays of 16 identical (Same) visual items from arrays of 16 nonidentical (Different) visual items, when the correct choice was conditional on the presence of another cue: the color of the background. In one experiment, pigeons rapidly learned this task and, after(More)
In Tribolium castaneum (CS) and T. confusum (CF), intra- and interspecific rates of homosexual mounting have been measured. The intraspecific results are compatible with the hypothesis of both species being sexually indiscriminate. However, the CF intraspecific rates were very high (35%-53% of mountings were homosexual), suggesting a lower sexual(More)
Four pigeons discriminated whether a target spot appeared on a colored figural shape or on a differently colored background by first pecking the target and then reporting its location: on the figure or the background. We recorded three dependent variables: target detection time, choice response time, and choice accuracy. The birds were faster to detect the(More)
Recent research has shown that the acquisition of a second cue–outcome association can interfere with responding appropriate to a previously acquired association between another cue and the same outcome, even if the two cues had never received compound training (Matute & Pineño, 1998a). This is similar to other results in the paired-associate literature but(More)
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(More)
Artificial divergent selection for the rate of homosexual copulation (defined as the proportion of homosexual mountings performed by a male in a period of 30 min) has been carried out for 2-3 generations in a population of Tribolium castaneum. A clear response was obtained in each of 4 replicates, corresponding to an overall realized heritability of 0.11 f(More)
We compared acquisition and performance accounts of human contingency learning. After solving a discrimination in Phase 1, in which Cue A predicted the occurrence of the outcome and Cue B predicted its nonoccurrence (A+/B-), a new discrimination (X+/Y-) was superimposed in Phase 2 (AX+/BY-). The participants were finally trained in Phase 3 with the added(More)
Prior research suggests that variability discrimination is basic to same-different conceptualization (Young and Wasserman, 2001). In that research, people were trained with 16-item arrays; this training might have encouraged people to use perceptual variability to solve the task. Here, two groups of participants were trained with either 2- or 16-item Same(More)