Papers by Victoria D. Chamizo
Behavioural Processes, 2017
The effects of early environmental enrichment (EE) when solving a simple spatial task in adult ma... more The effects of early environmental enrichment (EE) when solving a simple spatial task in adult male rats were assessed. After weaning, rats were housed in pairs in enriched or standard cages (EE and control groups) for two and a half months. Then the rats were trained in a triangular-shaped pool to find a hidden platform whose location was defined in terms of two sources of information, a landmark outside the pool and a particular corner of the pool. As expected, enriched rats reached the platform faster than control animals. Enriched rats also performed better on a subsequent test trial without the platform with the geometry cue individually presented (in the absence of the landmark). Most importantly, the beneficial effects of the present protocol were obtained in the absence of wheel running. Additionally, the antioxidative effects in the hippocampus produced by the previous protocol are also shown.
Encuentros multidisciplinares, 2022
El presente manuscrito aborda el complejo tema de la cognición espacial, donde es frecuente encon... more El presente manuscrito aborda el complejo tema de la cognición espacial, donde es frecuente encontrar diferencias de sexo (normalmente en beneficio del sexo masculino) desde edades tempranas. El trabajo comienza con una breve descripción de la figura de Sheryl Sorby y su magnífico legado, haciendo especial hincapié en su problema inicial, las proyecciones ortogonales. A continuación, se describe brevemente qué es una proyección ortogonal y su relación con la rotación mental. Se busca una explicación que permita entender las diferencias de sexo en las habilidades espaciales, insistiendo en las repercusiones que ello tiene, no solo en las carreras denominadas STEM (Ciencia, Tecnología, Ingeniería y Matemáticas), sino en todo el plan de estudios en general. El trabajo acaba mirando al futuro, con la esperanza de que todo el material de apoyo que está apareciendo en los últimos años, en buena medida gracias a las nuevas tecnologías, ayude en la eliminación de estas diferencias.
In two experiments in a virtual pool the participants were trained to find a hidden platform plac... more In two experiments in a virtual pool the participants were trained to find a hidden platform placed in a specific position in relation to one (Experiment 1) or two (Experiment 2) objects; then, all the participants received a test trial, without the platform, and the time spent in the segment where the platform should have been was measured. In Experiment 1, groups differed in the distance between the landmark and the hidden platform. Test results showed that the control acquired by the landmark was different depending on its relative distance from the platform: Closer landmarks acquired a better control than distant ones. In Experiment 2, two objects, B and F, were simultaneously present during acquisition. Object B was just above the hidden platform (i.e., a beacon for the platform) while object F was above the edge of the pool (i.e., a frame of reference). On the test, the spatial location of B in relation to F was manipulated in the different groups and a generalization gradient...
Frontiers in Psychology
There is much evidence, both in humans and rodents, that while navigating males tend to use geome... more There is much evidence, both in humans and rodents, that while navigating males tend to use geometric information whereas females rely more on landmarks. The present work attempts to alter the geometry bias in female rats. In Experiment 1 three groups of female rats were trained in a triangular-shaped pool to find a hidden platform, whose location was defined in terms of two sources of information, a landmark outside the pool and a particular corner of the pool. On a subsequent test trial with the triangular pool and no landmark, females with prior experience with two other pool shapes–with a kite-shaped pool and with a rectangular-shaped pool (Group Long Previous Experience, LPE), were significantly more accurate than control rats without such prior experience (Group No Previous Experience, NPE). Rats with a short previous experience–with the rectangular-shaped pool only (Group Short Previous Experience, SPE) did not differ from Group NPE. These results suggest that the previous ex...
In two experiments rats were trained to find an invisible platform in the presence of four object... more In two experiments rats were trained to find an invisible platform in the presence of four objects or landmarks which were centred at equal intervals around the edge of the pool. One pair of landmarks had more intrinsic salience than the other pair: The relative proximal from the platform landmarks were those with more intrinsic salience in Experiment 1 and those with less intrinsic salience in Experiment 2. In Experiment 1, the two proximal from the platform and with more intrinsic salience landmarks prevented learning about the two relatively distal from the platform and with less intrinsic salience landmarks. No sex differences were found. In Experiment 2, the two relatively distal and with more intrinsic salience landmarks did not prevent learning about the two proximal but with less intrinsic salience landmarks. No sex differences were found after extended training. These results have implications to understand spatial overshadowing among landmarks.
Journal of Experimental Psychology: Animal Learning and Cognition
In this article we addressed the question whether rats can use distal landmarks as directional cu... more In this article we addressed the question whether rats can use distal landmarks as directional cues that are used in combination with other proximal landmark configurations. The animals were trained with an A, B, C, and D landmark configuration in the Morris pool, where B and C are the near (to platform) landmarks and A and D the far ones. We also added another more distal "directional" cue Z (a white strip attached to the black curtain surrounding the pool). Experiment 1 shows a robust detrimental effect on the time spent by the rats swimming in the platform quadrant when the location of all landmarks was "Inverted" (rotated by 180 degrees) with respect to Z. A similar detrimental effect was found when, after the inversion manipulation, the locations of the near and far landmarks were "Flipped" (B swapped with C and A with D). Rats in both Inverted and Flipped tests spent more time in the Z quadrant compared to the platform quadrant (BC). Experiment 1b provided evidence distinguishing between alternative explanations of how the directional cue Z acts in combination with the other landmarks. The results from both experiments show that Z operates differently to the standard landmarks. It can function as a beacon in its own right. It can also combine with the other landmarks to produce a high level of search performance, in a way that we hypothesize to be distinct from that described by the configural analysis often applied to multiple landmarks.
Learning & Behavior
In three experiments, rats of different ages were trained in a circular pool to find a hidden pla... more In three experiments, rats of different ages were trained in a circular pool to find a hidden platform whose location was defined in terms of a single landmark, a cylinder outside the pool. Following training, two main components of the landmark, its shape and pattern, were tested individually. Experiment 1 was performed by adolescent and adult rats (Exp. 1a, males; Exp. 1b, females). Adult rats always learned faster than the adolescent animals. On test trials, interesting tendencies were found-mainly, one favoring males on the shape test trial, and another favoring females on the pattern test trial. Experiment 2 was conducted only with adolescent rats, and these males and females did not differ when learning the task. However, on test trials the males learned more about the landmark shape component than about the landmark pattern component, while the females learned equally about the two components of the landmark. Finally, Experiment 3 was conducted only with adult rats, and again the males and females did not differ when learning the task. However, on test trials the males learned equally about the two components of the landmark (shape and pattern), but the females learned more about the landmark pattern component than about the landmark shape component. This set of experiments supports the claim that male and female rats can learn rather different things about a landmark that signals the location of the platform, with age being a critical variable.
Learning & behavior, Jan 28, 2015
The effects of early environmental enrichment (EE) and voluntary wheel running on the preference ... more The effects of early environmental enrichment (EE) and voluntary wheel running on the preference for using a landmark or pool geometry when solving a simple spatial task in adult male and female rats were assessed. After weaning, rats were housed in same-sex pairs in enriched or standard cages (EE and control groups) for two and a half months. Then the rats were trained in a triangular-shaped pool to find a hidden platform whose location was defined in terms of these two sources of information, a landmark outside the pool and a particular corner of the pool. As expected, enriched rats reached the platform faster than control animals, and males and females did not differ. Enriched rats also performed better on subsequent test trials without the platform with the cues individually presented (either pool geometry or landmark). However, on a preference test without the platform, a clear sex difference was found: Females spent more time in an area of the pool that corresponded to the lan...
Psicologica Revista De Metodologia Y Psicologia Experimental, 2002
A growing body of evidence suggests that the spatial and the temporal domains seem to share the s... more A growing body of evidence suggests that the spatial and the temporal domains seem to share the same or similar conditions, basic effects, and mechanisms. The blocking, unblocking and overshadowing experiments (and also those of latent inhibition and perceptual learning reviewed by Prados and Redhead in this issue) show that to exclude associative learning as a basic mechanism responsible for spatial learning is quite inappropriate. All these results, especially those obtained with strictly spatial tasks, seem inconsistent with O'Keefe and Nadel's account of true spatial learning or locale learning. Their theory claims that this kind of learning is fundamentally different and develops with total independence from other ways of learning (like classical and instrumental conditioning-taxon learning). In fact, the results reviewed can be explained appealing on to a sophisticated guidance system, like for example the one proposed by Leonard and McNaughton (1990; see also McNaughton and cols, 1996). Such a system would allow that an animal generates new space information: given the distance and address from of A to B and from A to C, being able to infer the distance and the address from B to C, even when C is invisible from B (see Chapuis and Varlet, 1987-the contribution by McLaren in this issue constitutes a good example of a sophisticated guidance system).
In two experiments in a Morris pool rats were trained with a successive discrimination procedure ... more In two experiments in a Morris pool rats were trained with a successive discrimination procedure in the presence of two objects or landmarks. The angular separation between the two landmarks signalled either the presence (0 degrees, S+ trials) or the absence (90 degrees, S- trials) of the platform. After training the rats received unrewarded test trials in which one of
Se entrenó a unas ratas a encontrar una plataforma invisible definida por una configuración de do... more Se entrenó a unas ratas a encontrar una plataforma invisible definida por una configuración de dos objetos en la mitad de los ensayos y por una segunda configuración de dos objetos en la otra mitad. Los objetos estaban espaciados alrededor del borde de la piscina. Las dos configuraciones se presentaron con la misma frecuencia cada día, entremezcladas semi-al azar. En el Experimento 1, las configuraciones de las ratas fueron A y B (configuración 1), y B y C (configuración 2). B era un objeto común a ambas configuraciones. Al final de esta fase los animales recibieron ensayos de prueba en los que se colocaba a una rata en la piscina sin la plataforma y se registraba el tiempo que pasaba en el cuadrante de la plataforma. Los animales tuvieron ensayos de prueba con las configuraciones del entrenamiento, con los objetos por separado, y con una nueva configuración, A y C (una prueba de integración). Tanto ante las configuraciones del entrenamiento como en presencia de B, las ratas pasaron...
Learning and Motivation, 2006
ABSTRACT In two experiments in a Morris pool, rats were trained to find a hidden platform which w... more ABSTRACT In two experiments in a Morris pool, rats were trained to find a hidden platform which was located in a specific position in relation to two objects, B and F, which were presented together, one in front of the other. One object, B, was just above the platform (a beacon for the platform, the critical object) while the second object, F, was above the edge of the pool (the frame of reference). Then the rats received test trials, without the platform, in which B was presented in different positions in relation to F (i.e., in relation to its original position). In the two experiments the test results showed a generalization gradient as a function of the relative distance of the two objects: more time searching in the B segment, where the platform should have been, when B was in the original position (i.e., in front of F), which decreased symmetrically with distance of B from F. The present experiments show for the first time generalization gradients with rats across spatial locations when working with a navigation task.
Behavioural Processes, 2011
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...
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Papers by Victoria D. Chamizo