Quarterly journal of experimental psychology (2006), 2018
In three experiments, a virtual preparation for humans of the Morris water task (VMWT) was used. ... more In three experiments, a virtual preparation for humans of the Morris water task (VMWT) was used. Experiment 1 established that four landmarks were of similar salience. Then, in Experiments 2 and 3, participants were trained to locate a hidden platform in the presence or either two or four of the previous landmarks. In Experiment 2, one pair of groups was trained with four visual landmarks spaced at equal intervals around the edge of the pool, while a second pair was trained with two landmarks only, either relatively close to or far from the hidden platform. After training, a reciprocal overshadowing effect was found: on a test without the platform with two landmarks only (either close to or far from the platform position), the participants trained with four landmarks spent less time in the platform quadrant than those trained with only two. Finally, Experiment 3 showed that at least participants trained with two landmarks relatively close to the platform and then tested with four al...
Cholesterol reduction at the neuronal plasma membrane has been related to age-dependent cognitive... more Cholesterol reduction at the neuronal plasma membrane has been related to age-dependent cognitive decline. We have used senescent-accelerated mice strain 8 (SAMP8), an animal model for aging, to examine the association between cholesterol loss and cognitive impairment and to test strategies to revert this process. We show that the hippocampus of SAMP8 mice presents reduced cholesterol levels and enhanced amount of its degrading enzyme Cyp46A1 (Cyp46) already at 6 months of age. Cholesterol loss accounts for the impaired long-term potentiation in these mice. Plant sterol (PSE)-enriched diet prevents long-term potentiation impairment and cognitive deficits in SAMP8 mice without altering cholesterol levels. PSE diet also reduces the abnormally high amyloid peptide levels in SAMP8 mice brains and restores membrane compartmentalization of presenilin1, the catalytic component of the amyloidogenic γ-secretase. These results highlight the influence of cholesterol loss in age-related cognitive decline and provide with a noninvasive strategy to counteract it. Our results suggest that PSE overtake cholesterol functions in the brain contributing to reduce deleterious consequences of cholesterol loss during aging.
O´Keefe y Nadel (1978) consideran que un mapa cognitivo es una representación del entorno en la q... more O´Keefe y Nadel (1978) consideran que un mapa cognitivo es una representación del entorno en la que se incluye toda la información disponible respecto a los puntos de referencia y sus relaciones espaciales. Una vez formado el mapa cognitivo, los animales pueden utilizar cualquier subconjunto de puntos de referencia para localizar una meta. El experimento que se presenta pretende analizar si efectivamente un mapa cognitivo incluye toda la información del medio o sólo la información que es más relevante para localizar una meta invisible. Para este objetivo se entrenó a dos grupos de ratas a localizar una plataforma invisible ubicada en una piscina de Morris. Uno de los grupos disponía de cuatro puntos de referencia (A, B, C, D) mientras que el segundo grupo aprendió la tarea en presencia de dos puntos de referencia (C, D). Después del entrenamiento, ambos grupos se sometieron a una prueba en la que se les permitía nadar en la piscina con sólo dos puntos de referencia (C, D) y sin la p...
Relational learning transference in a navigation task. Three groups of rats were trained to find ... more Relational learning transference in a navigation task. Three groups of rats were trained to find a hidden platform located in a fixed position relative to four landmarks surrounding a swimming pool. The group No Change received active preexposure (Prados, Redhead & Pearce, 1999) to the same landmarks (ABCD) that define the location of the platform during the training. The group Change, received active preexposure to a set of four landmarks (LMNO) different to the one used to define the platform location during training (ABCD). Finally, the Control group was preexposed to the apparatus and then trained to find the platform by reference to ABCD. The preexposed groups showed a facilitated learning when searching for the invisible platform. The performance of the group Change could be said to demonstrate that learning to attend to the spatial relation between the landmarks that were present during preexposure was transferred to the new landmarks presented during the training phase. Thes...
O'Keefe y Nadel (1978) consideran que un mapa cognitivo es una representación del entorno en ... more O'Keefe y Nadel (1978) consideran que un mapa cognitivo es una representación del entorno en la que se incluye toda la información disponible respecto a los puntos de referencia y sus relaciones espaciales. Una vez formado el mapa cognitivo, los animales pueden utilizar cualquier subconjunto de puntos de referencia para localizar una meta. El experimento que se presenta pretende analizar
Quarterly Journal of Experimental Psychology, 2014
A theory or model of cause such as Cheng's power ( p) allows people to predict the effectiven... more A theory or model of cause such as Cheng's power ( p) allows people to predict the effectiveness of a cause in a different causal context from the one in which they observed its actions. Liljeholm and Cheng demonstrated that people could detect differences in the effectiveness of the cause when causal power varied across contexts of different outcome base rates, but that they did not detect similar changes when only the cause–outcome contingency, ∆ p, but not power, varied. However, their procedure allowed participants to simplify the causal scenarios and consider only a subsample of observations with a base rate of zero. This confounds p, ∆ p, and the probability of an outcome (O) given a cause (C), P(O|C). Furthermore, the contingencies that they used confounded p and P(O|C) in the overall sample. Following the work of Liljeholm and Cheng, we examined whether causal induction in a wider range of situations follows the principles suggested by Cheng. Experiments 1a and 1b compar...
Quarterly Journal of Experimental Psychology, 2010
In two experiments, we studied the strategies that people use to discover causal relationships. A... more In two experiments, we studied the strategies that people use to discover causal relationships. According to inferential approaches to causal discovery, if people attempt to discover the power of a cause, then they should naturally select the most informative and unambiguous context. For generative causes this would be a context with a low base rate of effects generated by other causes and for preventive causes a context with a high base rate. In the following experiments, we used probabilistic and/or deterministic target causes and contexts. In each experiment, participants observed several contexts in which the effect occurred with different probabilities. After this training, the participants were presented with different target causes whose causal status was unknown. In order to discover the influence of each cause, participants were allowed, on each trial, to choose the context in which the cause would be tested. As expected by inferential theories, the participants preferred t...
Quarterly Journal of Experimental Psychology, 2006
In three experiments rats were given short or long preexposure (4 or 10 sessions) to two compound... more In three experiments rats were given short or long preexposure (4 or 10 sessions) to two compound flavours, AX and BX, according to an intermixed or a blocked schedule. Following preexposure, aversion conditioning trials were given with AX as the conditioned stimulus (CS). In Experiments 1 and 2, retardation and summation tests were then carried out to assess the inhibitory properties of B (an Espinet procedure). In Experiment 3, test trials evaluated generalization from AX to BX (the standard perceptual learning procedure). The results showed that B performed as an inhibitor of the unconditioned stimulus (US; an Espinet effect) only after long intermixed preexposure, whereas a reliable perceptual learning effect was observed both after short and after long preeexposure. The observation that B had no detectable inhibitory properties after short preexposure casts doubt on the suggestion that inhibitory learning is responsible for perceptual learning after brief exposure to AX and BX.
Journal of Experimental Psychology: Animal Behavior Processes, 2007
In 4 experiments, rats were given intermixed or blocked preexposure to an array of landmarks that... more In 4 experiments, rats were given intermixed or blocked preexposure to an array of landmarks that subsequently defined the location of a hidden goal in a Morris pool task. Previous research has shown that intermixed preexposure to pairs of adjacent landmarks retards learning whereas preexposure to individual landmarks facilitates subsequent learning (J. Prados, V. D. Chamizo, & N. J. Mackintosh, 1999). Accordingly, in Experiment 1, intermixed and blocked preexposure to pairs of adjacent landmarks was found to retard learning. In Experiment 2, however, a scheduling effect was found: Rats given intermixed preexposure to the individual landmarks learned faster than rats given blocked or no preexposure. Experiment 3 showed that intermixed (but not blocked) preexposure to pairs of landmarks resulted in a facilitatory effect when preexposure and test were carried out in different contexts. Experiment 4 replicated within a single experiment the main results observed in Experiments 1 and 3. This pattern of results suggests that intermixed preexposure engages learning processes other than latent inhibition that facilitate subsequent learning of the navigation task.
Journal of Experimental Psychology: Animal Behavior Processes, 2012
In three experiments rats were given serial preexposure to two flavor stimuli. In Experiment 1, s... more In three experiments rats were given serial preexposure to two flavor stimuli. In Experiment 1, some animals were given exposure to AX followed by the presentation of BX, a forward schedule; the others were given backward preexposure (BX→AX). Conditioning and test trials with the A element showed that salience or effectiveness of A was better protected in the forward than in the backward condition. Experiments 2 and 3 assessed the relevance of this salience modulation mechanism for perceptual learning. In these experiments, generalization of a conditioned aversion from AX to BX was reduced in the forward (but not in the backward) condition only after prolonged exposure, indicating that the establishment of an inhibitory link from B to A is required for successful discrimination. However, generalization to a novel compound stimulus, NX, was reduced in the forward group both after short and long preexposure, suggesting the existence of salience modulation processes that work in parallel with associative inhibition. These results seem to support the existence of a salience modulation mechanism that seems to be beyond the scope of current theories of perceptual learning.
We used a new virtual program in two experiments to prepare subjects to perform the Morris water ... more We used a new virtual program in two experiments to prepare subjects to perform the Morris water task (www.nesplora.com). The subjects were Psychology students; they were trained to locate a safe platform amidst the presence of four pinpoint landmarks spaced around the edge of the pool (i.e., two landmarks relatively near the platform and two landmarks relatively distant away from it). At the end of the training phase, we administered one test trial without the platform and recorded the amount of time that the students had spent in the platform quadrant. In Experiment 1, we conducted the test trial in the presence of one or two of the distant landmarks. When only one landmark was present during testing, performance fell to chance. However, the men outperformed the women when the two distant landmarks were both present. Experiment 2 replicated the previous results and extended it by showing that no sex differences exist when the searching process is based on the near landmarks. Both the men and the women had similarly good performances when the landmarks were present both individually and together. When present together, an addition effect was found. Far landmark tests favor configural learning processes, whereas near landmark tests favor elemental learning. Our findings suggest that other factors in addition to the use of directional cues can underlie the sex differences in the spatial learning process. Thus, we expand upon previous research in the field.
Quarterly journal of experimental psychology (2006), 2018
In three experiments, a virtual preparation for humans of the Morris water task (VMWT) was used. ... more In three experiments, a virtual preparation for humans of the Morris water task (VMWT) was used. Experiment 1 established that four landmarks were of similar salience. Then, in Experiments 2 and 3, participants were trained to locate a hidden platform in the presence or either two or four of the previous landmarks. In Experiment 2, one pair of groups was trained with four visual landmarks spaced at equal intervals around the edge of the pool, while a second pair was trained with two landmarks only, either relatively close to or far from the hidden platform. After training, a reciprocal overshadowing effect was found: on a test without the platform with two landmarks only (either close to or far from the platform position), the participants trained with four landmarks spent less time in the platform quadrant than those trained with only two. Finally, Experiment 3 showed that at least participants trained with two landmarks relatively close to the platform and then tested with four al...
Cholesterol reduction at the neuronal plasma membrane has been related to age-dependent cognitive... more Cholesterol reduction at the neuronal plasma membrane has been related to age-dependent cognitive decline. We have used senescent-accelerated mice strain 8 (SAMP8), an animal model for aging, to examine the association between cholesterol loss and cognitive impairment and to test strategies to revert this process. We show that the hippocampus of SAMP8 mice presents reduced cholesterol levels and enhanced amount of its degrading enzyme Cyp46A1 (Cyp46) already at 6 months of age. Cholesterol loss accounts for the impaired long-term potentiation in these mice. Plant sterol (PSE)-enriched diet prevents long-term potentiation impairment and cognitive deficits in SAMP8 mice without altering cholesterol levels. PSE diet also reduces the abnormally high amyloid peptide levels in SAMP8 mice brains and restores membrane compartmentalization of presenilin1, the catalytic component of the amyloidogenic γ-secretase. These results highlight the influence of cholesterol loss in age-related cognitive decline and provide with a noninvasive strategy to counteract it. Our results suggest that PSE overtake cholesterol functions in the brain contributing to reduce deleterious consequences of cholesterol loss during aging.
O´Keefe y Nadel (1978) consideran que un mapa cognitivo es una representación del entorno en la q... more O´Keefe y Nadel (1978) consideran que un mapa cognitivo es una representación del entorno en la que se incluye toda la información disponible respecto a los puntos de referencia y sus relaciones espaciales. Una vez formado el mapa cognitivo, los animales pueden utilizar cualquier subconjunto de puntos de referencia para localizar una meta. El experimento que se presenta pretende analizar si efectivamente un mapa cognitivo incluye toda la información del medio o sólo la información que es más relevante para localizar una meta invisible. Para este objetivo se entrenó a dos grupos de ratas a localizar una plataforma invisible ubicada en una piscina de Morris. Uno de los grupos disponía de cuatro puntos de referencia (A, B, C, D) mientras que el segundo grupo aprendió la tarea en presencia de dos puntos de referencia (C, D). Después del entrenamiento, ambos grupos se sometieron a una prueba en la que se les permitía nadar en la piscina con sólo dos puntos de referencia (C, D) y sin la p...
Relational learning transference in a navigation task. Three groups of rats were trained to find ... more Relational learning transference in a navigation task. Three groups of rats were trained to find a hidden platform located in a fixed position relative to four landmarks surrounding a swimming pool. The group No Change received active preexposure (Prados, Redhead & Pearce, 1999) to the same landmarks (ABCD) that define the location of the platform during the training. The group Change, received active preexposure to a set of four landmarks (LMNO) different to the one used to define the platform location during training (ABCD). Finally, the Control group was preexposed to the apparatus and then trained to find the platform by reference to ABCD. The preexposed groups showed a facilitated learning when searching for the invisible platform. The performance of the group Change could be said to demonstrate that learning to attend to the spatial relation between the landmarks that were present during preexposure was transferred to the new landmarks presented during the training phase. Thes...
O'Keefe y Nadel (1978) consideran que un mapa cognitivo es una representación del entorno en ... more O'Keefe y Nadel (1978) consideran que un mapa cognitivo es una representación del entorno en la que se incluye toda la información disponible respecto a los puntos de referencia y sus relaciones espaciales. Una vez formado el mapa cognitivo, los animales pueden utilizar cualquier subconjunto de puntos de referencia para localizar una meta. El experimento que se presenta pretende analizar
Quarterly Journal of Experimental Psychology, 2014
A theory or model of cause such as Cheng's power ( p) allows people to predict the effectiven... more A theory or model of cause such as Cheng's power ( p) allows people to predict the effectiveness of a cause in a different causal context from the one in which they observed its actions. Liljeholm and Cheng demonstrated that people could detect differences in the effectiveness of the cause when causal power varied across contexts of different outcome base rates, but that they did not detect similar changes when only the cause–outcome contingency, ∆ p, but not power, varied. However, their procedure allowed participants to simplify the causal scenarios and consider only a subsample of observations with a base rate of zero. This confounds p, ∆ p, and the probability of an outcome (O) given a cause (C), P(O|C). Furthermore, the contingencies that they used confounded p and P(O|C) in the overall sample. Following the work of Liljeholm and Cheng, we examined whether causal induction in a wider range of situations follows the principles suggested by Cheng. Experiments 1a and 1b compar...
Quarterly Journal of Experimental Psychology, 2010
In two experiments, we studied the strategies that people use to discover causal relationships. A... more In two experiments, we studied the strategies that people use to discover causal relationships. According to inferential approaches to causal discovery, if people attempt to discover the power of a cause, then they should naturally select the most informative and unambiguous context. For generative causes this would be a context with a low base rate of effects generated by other causes and for preventive causes a context with a high base rate. In the following experiments, we used probabilistic and/or deterministic target causes and contexts. In each experiment, participants observed several contexts in which the effect occurred with different probabilities. After this training, the participants were presented with different target causes whose causal status was unknown. In order to discover the influence of each cause, participants were allowed, on each trial, to choose the context in which the cause would be tested. As expected by inferential theories, the participants preferred t...
Quarterly Journal of Experimental Psychology, 2006
In three experiments rats were given short or long preexposure (4 or 10 sessions) to two compound... more In three experiments rats were given short or long preexposure (4 or 10 sessions) to two compound flavours, AX and BX, according to an intermixed or a blocked schedule. Following preexposure, aversion conditioning trials were given with AX as the conditioned stimulus (CS). In Experiments 1 and 2, retardation and summation tests were then carried out to assess the inhibitory properties of B (an Espinet procedure). In Experiment 3, test trials evaluated generalization from AX to BX (the standard perceptual learning procedure). The results showed that B performed as an inhibitor of the unconditioned stimulus (US; an Espinet effect) only after long intermixed preexposure, whereas a reliable perceptual learning effect was observed both after short and after long preeexposure. The observation that B had no detectable inhibitory properties after short preexposure casts doubt on the suggestion that inhibitory learning is responsible for perceptual learning after brief exposure to AX and BX.
Journal of Experimental Psychology: Animal Behavior Processes, 2007
In 4 experiments, rats were given intermixed or blocked preexposure to an array of landmarks that... more In 4 experiments, rats were given intermixed or blocked preexposure to an array of landmarks that subsequently defined the location of a hidden goal in a Morris pool task. Previous research has shown that intermixed preexposure to pairs of adjacent landmarks retards learning whereas preexposure to individual landmarks facilitates subsequent learning (J. Prados, V. D. Chamizo, & N. J. Mackintosh, 1999). Accordingly, in Experiment 1, intermixed and blocked preexposure to pairs of adjacent landmarks was found to retard learning. In Experiment 2, however, a scheduling effect was found: Rats given intermixed preexposure to the individual landmarks learned faster than rats given blocked or no preexposure. Experiment 3 showed that intermixed (but not blocked) preexposure to pairs of landmarks resulted in a facilitatory effect when preexposure and test were carried out in different contexts. Experiment 4 replicated within a single experiment the main results observed in Experiments 1 and 3. This pattern of results suggests that intermixed preexposure engages learning processes other than latent inhibition that facilitate subsequent learning of the navigation task.
Journal of Experimental Psychology: Animal Behavior Processes, 2012
In three experiments rats were given serial preexposure to two flavor stimuli. In Experiment 1, s... more In three experiments rats were given serial preexposure to two flavor stimuli. In Experiment 1, some animals were given exposure to AX followed by the presentation of BX, a forward schedule; the others were given backward preexposure (BX→AX). Conditioning and test trials with the A element showed that salience or effectiveness of A was better protected in the forward than in the backward condition. Experiments 2 and 3 assessed the relevance of this salience modulation mechanism for perceptual learning. In these experiments, generalization of a conditioned aversion from AX to BX was reduced in the forward (but not in the backward) condition only after prolonged exposure, indicating that the establishment of an inhibitory link from B to A is required for successful discrimination. However, generalization to a novel compound stimulus, NX, was reduced in the forward group both after short and long preexposure, suggesting the existence of salience modulation processes that work in parallel with associative inhibition. These results seem to support the existence of a salience modulation mechanism that seems to be beyond the scope of current theories of perceptual learning.
We used a new virtual program in two experiments to prepare subjects to perform the Morris water ... more We used a new virtual program in two experiments to prepare subjects to perform the Morris water task (www.nesplora.com). The subjects were Psychology students; they were trained to locate a safe platform amidst the presence of four pinpoint landmarks spaced around the edge of the pool (i.e., two landmarks relatively near the platform and two landmarks relatively distant away from it). At the end of the training phase, we administered one test trial without the platform and recorded the amount of time that the students had spent in the platform quadrant. In Experiment 1, we conducted the test trial in the presence of one or two of the distant landmarks. When only one landmark was present during testing, performance fell to chance. However, the men outperformed the women when the two distant landmarks were both present. Experiment 2 replicated the previous results and extended it by showing that no sex differences exist when the searching process is based on the near landmarks. Both the men and the women had similarly good performances when the landmarks were present both individually and together. When present together, an addition effect was found. Far landmark tests favor configural learning processes, whereas near landmark tests favor elemental learning. Our findings suggest that other factors in addition to the use of directional cues can underlie the sex differences in the spatial learning process. Thus, we expand upon previous research in the field.
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Papers by Joan Sansa