Biomedical subjects

Juan M Rosas

Publications and source records attributed to Juan M Rosas.

6 recordsLinked to original sources

PubMed2007

Acquisition of a conditioned taste aversion becomes context dependent when it is learned after extinction.

A conditioned taste aversion experiment tested context-switch effects on retrieval of conditioned stimulus (CS)-unconditioned stimulus (US) acquisition performance in rats. A context switch impaired performance when the target flavour was trained in a context where a different flavour underwent extinction. Conditioned taste aversion in the absence of previous extinction of the alternate flavour was not context dependent. It is suggested that the ambiguity in the meaning of the extinguished cue leads animals to pay attention to the context, so that the information learned in that context becomes context dependent.

Analysis of Variance↗

PubMed2006

Acquisition, extinction and temporal discrimination in human conditioned avoidance.

Two experiments were conducted with the aim of designing a videogame for the study of human conditioned avoidance. Participants had to destroy enemy spaceships with the goal of increasing the score in a counter. Coloured signals might announce the launching of a bomb that could hit participant's spaceship producing a 30 points decrease in participant's score. Three groups of participants were trained in discriminating between a warning signal (W) and a safety signal (S) in Experiment 1. Instrumental group could avoid the loss of points by hiding the spaceship before the offset of W. Participants in the Yoked group received the same treatment received by their instrumental partners, regardless of their behaviour. In the Pavlovian group, W was always followed by the loss of points, regardless of participant's behaviour. Discrimination between W and S was better in the Instrumental groups than in the Yoked and Pavlovian control groups. Experiment 2 found extinction of avoidance when the warning signal was not followed by the bomb. Temporal discrimination was found within the participants that received the instrumental contingency in both experiments, with higher avoidance response towards the end of the warning signal. Temporal discrimination disappeared after extinction in Experiment 2.

Adult↗

PubMed2006

Context switch effects on acquisition and extinction in human predictive learning.

Four experiments tested context switch effects on acquisition and extinction in human predictive learning. A context switch impaired probability judgments about a cue-outcome relationship when the cue was trained in a context in which a different cue underwent extinction. The context switch also impaired judgments about a cue trained in a context different from the extinction context, whenever this training was concurrent with extinction of another cue. After extinction, new cue-outcome relationships learned, even in a different task, became context specific. Moreover, renewal was consistently observed. It is suggested that context switch effects result from a process by which ambiguity leads participants to attend to the contexts.

Adolescent↗

PubMed2003

Empirical and theoretical implications of additivity between reinstatement and renewal after interference in causal learning.

An experiment explored the effects of context change (renewal) and presentation of the outcome (reinstatement) upon retroactive interference in causal learning. An interference task was used where a sequential relationship between the name of a food and two different outcomes was established (A+|A*). Renewal and reinstatement effects appeared as partial attenuation of retroactive interference. The combination of both treatments produced complete recovery of first-learned information (A+). This complete reversal on the estimations of participants suggests that renewal and reinstatement effects within this paradigm imply partial recovery of the first-learned information, rather than response at a chance level emitted by confused participants. On the other hand, additivity between reinstatement and renewal suggests that reinstatement may be due to the combined effect of different underlying processes.

Journal Article↗

PubMed2003

Context change as the mechanism of reinstatement in causal learning.

Four experiments were conducted to explore the mechanism of reinstatement in human causal learning. After a retroactive interference treatment in which a stimulus was first followed by an outcome (A+) and then followed by a different outcome (A*), simple exposure to the original outcome (+) in the interference-test context produced partial reinstatement of the first-learned information (A+). When exposure to the outcome took place in a context different from the interference-test context, reinstatement was not observed (Experiment 1). Equivalent results appeared when the outcome presented during reinstatement was different from the one originally related to the stimulus affected by interference, independent of whether the interfering outcome (Experiments 2, 3, and 4) or a new outcome (Experiments 3 and 4) was presented before the test. These results suggest an interpretation of reinstatement in terms of a context change between interference and testing.

Adolescent↗

PubMed2002

Transfer of control between causal predictive judgments and instrumental responding.

Four experiments were conducted to explore outcome-specific transfer from causal predictive judgments to instrumental responding. A video game was designed in which participants had to defend Andalusia from navy and air force attacks. First, they learned the relationship between two instrumental responses (two key on a standard keyboard) and two different outcomes (destruction of the ships or destruction of the planes). Then they learned to predict which of two different stimuli predicted which outcome. Finally, they had the opportunity of making either of the two instrumental responses in the presence of either stimulus. Transfer was shown as a preference for the response that shared an outcome with the current stimulus. The presentation of the stimulus during the test produced a decrease in the overall rate of response. Responding to a neutral stimulus in Experiments 2 and 3 suggested that this overall decrease in responding was due to a combination of the time needed to process the meaning of the stimulus and the activation of the representation of the outcome in the presence of the stimulus during the test. Transfer between predictive judgments and instrumental responding mirrors the outcome-specific Pavlovian instrumental transfer observed in conditioning studies with rats.

Adolescent↗