Cástor Méndez

Comparing direct and indirect measures of sequence learning.

Comparing the sensitivity of similar direct and indirect measures is proposed as the best way to provide evidence for unconscious learning. The authors apply this approach, first proposed by E. M. Reingold and P. M. Merikle (1988), to a choice reaction-time task in which the material is generated probabilistically on the basis of a finite-state grammar (A. Cleeremans, 1993). The data show that participants can learn about the structure of the stimulus material over training with the choice reaction-time task, but only to a limited extent - a result that is well predicted by the simple recurrent network model of A. Cleeremans and J. L. McClelland (1991). Participants can also use some of this knowledge to perform a subsequent generation task. However, detailed partial correlational analyses that control for knowledge as assessed by the generation task show that large effects of sequence learning are exclusively expressed through reaction time. This result suggests that at least some of this learning cannot be characterized as conscious.

Implicit sequence learning with competing explicit cues

Previous research has shown that the expression of implicit sequence learning is eliminated in a choice reaction time task when an explicit cue allows participants to accurately predict the next stimulus (Cleeremans, 1997), but that two contingencies predicting the same outcome can be learned and expressed simultaneously when both of them remain implicit (Jiménez & Méndez, 1999). Two experiments tested the hypothesis that it is the deliberate use of explicit knowledge that produces the inhibitory effects over the expression of implicit sequence learning. However, the results of these experiments do not support this hypothesis, rather showing that implicit learning is acquired and expressed regardless of the influence of explicit knowledge. These results are interpreted as reinforcing the thesis about the automatic nature of both the acquisition and the expression of implicit sequence learning. The contradictory results reported by Cleeremans are attributed to a floor effect derived from the use of a special type of explicit cue.

Contextual fear conditioning differs for infant, adolescent, and adult rats

Contextual fear conditioning was tested in infant, adolescent, and adult rats in terms of Pavlovian-conditioned suppression. When a discrete auditory-conditioned stimulus (CS) was paired with footshock (unconditioned stimulus, US) within the largely olfactory context, infants and adolescents conditioned to the context with substantial effectiveness, but adult rats did not. When unpaired presentations of the CS and US occurred within the context, contextual fear conditioning was strong for adults, weak for infants, but about as strong for adolescents as when pairings of CS and US occurred in the context. Nonreinforced presentations of either the CS or context markedly reduced contextual fear conditioning in infants, but, in adolescents, CS extinction had no effect on contextual fear conditioning, although context extinction significantly reduced it. Neither CS extinction nor context extinction affected responding to the CS-context compound in infants, suggesting striking discrimination between the compound and its components. Female adolescents showed the same lack of effect of component extinction on response to the compound as infants, but CS extinction reduced responding to the compound in adolescent males, a sex difference seen also in adults. Theoretical implications are discussed for the development of perceptual-cognitive processing and hippocampus role.

Automatic imitation and spatial compatibility in a key-pressing task.

Automatic imitation has been often confounded with spatial compatibility effects. Heyes (2011) called attention to this confound, and proposed some criteria which must be satisfied before these effects could be unequivocally taken to be an index of the functioning of the human mirror system. Evidence satisfying such criteria has been reported by Catmur and Heyes (2011), using a relatively unfamiliar finger abduction movement. However, because many previous studies relied on more familiar actions, we aimed at testing whether analogous effects could be obtained with a more practiced key-pressing task. In Experiment 1, we used anatomical controls (i.e., views of right vs. left hands) under conditions affording mirror imitation, and showed that spatial compatibility masked the effects of automatic imitation. Experiment 2 used rotated conditions to control for this spatial-anatomical confound, and it showed unequivocal effects of automatic imitation, which were obtained regardless of its relation to the spatial stimulus-response mapping. These results cast some doubts on the interpretation of previous reports relying exclusively on scenes presented from a mirror perspective, and suggest the convenience of using both rotated scenes and anatomical controls in order to assess automatic imitation.

Emulation and Mimicry in School Students with Typical Development and with High Functioning Autism.

Two samples of participants with typical development (TD) and high functioning autism performed an imitation task where the goal was of high or low salience, and where the modeled action complied with or was contrary to the end-state comfort (ESC) effect. Imitation was affected by the ESC effect in both groups, and participants with autism reproduced high salient goals as frequently as did participants with TD, but they reproduced less of the low salient goals. Participants with autism showed a reduced tendency to reproduce those actions which were relatively inefficient to reach the goals. The results are discussed in terms of either a relative imbalance between emulation and mimicry in autism, or a reduced tendency to overimitate.

Condicionamiento con estimulos enmascarados: Desarrollo de Efectos de Priming como Evidencia de Aprendizaje Asociativo no Consciente.

ResumenLos argumentos tradicionales de la discusion sobre el papel del procesamiento consciente en el condicionamiento clasico humano se revisan a la luz de los resultados de aprendizaje no consciente obtenidos recientemente en el campo del aprendizaje implicito. Tomando en cuenta las limitaciones de los argumentos teoricos y experimentales que sustentan la «necessary-gate hypothesis» (Dawson y Furedy, 1976), se proponen dos explicaciones alternativas que incluyen la posibilidad de obtener efectos de aprendizaje no consciente. Estas explicaciones se ponen a prueba a traves de un estudio experimental de condicionamiento semantico en el que se emplean tecnicas de enmascaramiento retroactivo para evitar la percepcion consciente del Estimulo Condicionado (EC), del Estimulo Incondicionado (EI) o de ambos, obteniendo claros efectos de aprendizaje asociativo no consciente en los grupos en los que solo uno de los dos estimulos puede ser procesado conscientemente, cuando este efecto se mide a traves de indices ind...

Aprendizaje implícito: tres aproximaciones a la cuestión del aprendizaje sin conciencia

ResumenLos tres paradigmas mas importantes desarrollados en el area del aprendizaje implicito son revisados a la luz de la definicion recientemente planteada por Reber (1993) d este conocimiento como aquel que se produce independientemente de los intentos conscientes por aprender, y en ausencia de un reconocimiento explicito de sus resultados. Se repasan los estudios empiricos mas relevantes llevados a cabo siguiendo cada uno de estos tres paradigmas, y se discute el grado en que podria asumirse para cada uno de ellos el cumplimiento de estos requisitos, concluyendo que seria el paradigma de aprendizaje secuencial el unico en el que se habria demostrado suficientemente la existencia de un proceso implicito de aprendizaje. Los recientes intentos de elaborar modelos computacionales de los mecanismos responsables de estos aprendizajes se senalan, por ultimo, como un enfoque alternativo a este mismo problema de delimitacion de los procesos de aprendizaje asociativo no consciente, que podrian ayudar a comprend...