Assessing the inhibitory properties of a latent inhibitor in flavor-aversion learning.

In Experiment 1, rats received 16 nonreinforced trials of exposure to a flavor (A) that was subsequently used as the conditioned stimulus in flavor-aversion conditioning. In the critical condition, Flavor A was presented in compound with a different novel flavor on each of the eight daily trials. This treatment produced latent inhibition, in that this preexposure retarded conditioning just as did 16 trials with A alone. Rats in the control conditions, given no preexposure or exposure just to the sequence of novel flavors, learned readily. Experiment 2 examined the effects of these forms of preexposure on performance on a summation test, in which Flavor A was presented in compound with a separately conditioned flavor (X). The preexposure procedure in which A was presented along with novel flavors rendered A effective in inhibiting the response conditioned to X on that test. The conclusion, that this form of training can establish the target stimulus as a conditioned inhibitor, is predicted by the account of latent inhibition put forward by Hall and Rodríguez (2010) which proposes that the latent inhibition effect is a consequence both of a reduction in the associability of the stimulus and of a process of inhibitory associative learning that opposes the initial expectation that a novel event will be followed by some consequence.

Reconsidering the ability of the stimulus unique features to capture attention: Evidence from change blindness and visual search paradigms.

In Experiment 1 (change blindness), participants received either intermixed or blocked presentations of two visual stimuli that contained several common (X) and unique (A or B) features. On the critical trial after exposure, the stimulus AX was presented but included an unexpected visual event (a change in the size of a stimulus feature). We found that participants readily detected the change when it involved an A-unique feature that had been preexposed intermixed. However, if the change involved an A-unique feature preexposed in blocks, or an X-common feature (preexposed either intermixed or in blocks), the level of the detections considerably decreased. In Experiment 2, after either intermixed or blocked preexposure to AX and BX, all the participants were instructed to search for an unrelated visual target item. In the distractor condition, during the development of the search task, the A-unique feature emerged at an unpredictable location that was different to that occupied by this feature during the preexposure. In the control condition, the target was presented on its own during the entire task. The presence of the A-unique feature only produced a detrimental effect on search performance when the AX and BX had been preexposed intermixed. These results are discussed as indicative of the intermixed preexposure schedule enhancing the ability of the stimulus unique features to capture involuntary attention. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Inhibitory properties of a latent inhibitor after preexposure in compound with novel stimuli.

Latent inhibition refers to retardation of the development of a conditioned response when the conditioned stimulus (CS) is preexposed alone prior to its pairings with an unconditioned stimulus. Experiment 1 demonstrated this effect for rats trained in an appetitive conditioning procedure and confirmed that the effect is found when the target stimulus is presented in compound with another or with a range of other stimuli during preexposure. Previous work has shown that a latent inhibitor does not reliably reduce the level of conditioned responding supported by an excitatory CS when the 2 stimuli are presented in compound (in a summation test). In Experiments 2, 3, and 4 we demonstrate that preexposure in which the target stimulus is presented in compound with a novel event on every trial will render that stimulus effective in a summation test. This outcome is uniquely predicted by the account of latent inhibition proposed by Hall and Rodríguez (2010), which suggests that the latent inhibition effect is a consequence both of a reduction in the associability of the stimulus and of a process of inhibitory associative learning that opposes the initial expectation that a novel event will be followed by some consequence. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Loss of salience as a source of latent inhibition in human associative learning.

Two experiments made use of a procedure known to generate latent inhibition in human associative learning. Participants received training consisting of exposure to a list of actions performed by a fictitious Mr. X. For most of his actions, an outcome was described, but some were not followed by any outcome. The last action performed by Mr. X was novel for participants in the NOVEL condition. For participants in the EXPOSED condition, Mr. X had performed that target action on repeated occasions, without it producing any outcome. After training, all participants were tested on their ability to retrieve what was the last action performed by Mr. X. In both experiments, retrieval of the target action was poorer in the EXPOSED than in the NOVEL condition. Experiment 2 also included a condition in which the target action was followed by a novel outcome and demonstrated a latent inhibition effect-poorer performance in the EXPOSED condition on a test of the association between the target event and its outcome. These results are interpreted in terms of an attention-reducing mechanism, triggered by the repeated preexposure to the target in the absence of a following event. It is argued that the attentional change involves a reduction in the effective salience of the stimulus of the target event, and thus reduces the processing necessary for encoding in memory and the ability of the event to enter into associations.

El efecto de fiabilidad predictiva en aprendizaje causal humano no se ve afectado por el sobreentrenamiento / The effect of predictive reliability on human causal learning is not affected by overtraining

Resumen Los estudios previos en aprendizaje causal humano han demostrado que la historia predictiva de los estímulos influye en su asociabilidad (es decir, en la facilidad con la que estos entran posteriormente en asociaciones). En la Fase 1 de estos estudios, se dan las condiciones para que los participantes aprendan que la mitad de los estímulos son predictores fiables de sus resultados y la otra mitad son predictores no fiables. En la Fase 2, todos los estímulos se emparejan por igual con nuevos resultados. Se ha observado consistentemente que los participantes estiman que la probabilidad de ocurrencia de los resultados de la Fase 2 es más probable en presencia de los predictores fiables de la Fase 1 que en presencia de los no fiables. Se presenta un experimento en el que se demuestra que una reducción en el entrenamiento de la Fase 1 no afecta a la magnitud de este efecto de fiabilidad predictiva. Este resultado es inconsistente con la idea de que el efecto de fiabilidad predictiva se produce a consecuencia de cambios en la asociabilidad de los estímulos durante la Fase 1. Se discute una interpretación alternativa del efecto en términos del aprendizaje y generalización de reglas de actuación en la tarea.

Abstract Previous studies in human causal learning have demonstrated that the predictive history of the stimuli influences their associability (i.e., readiness with which they enter into associations subsequently). Participants receive initial training in which they can learn that half of the cues are accurate predictors of their outcomes, and the other half are poorer predictors (Stage 1). Subsequently, all cues are equally predictive of a new outcome (Stage 2). On test, participants rate the likelihood that the cues would produce Stage 2 outcomes. It has been consistently found that participants rate the cues that were accurate predictors in Stage 1 higher than poorer predictors. A new experiment is reported demonstrating that a reduction of the length of Stage 1 training does not affect the magnitude of this predictive accuracy effect. This finding is inconsistent with the notion that the effect is a consequence of changes in the associability of the cues on Stage 1. An alternative interpretation of the effect in terms of learning and generalization of performance rules of is considered.