What makes a landmark effective? Sex differences in a navigation task

In Experiment 1, two groups of female rats were trained in a triangular pool to find a hidden platform whose location was defined in terms of a single a landmark, a cylinder outside the pool. For one group, the landmark had only a single pattern (i.e., it looked the same when approached from any direction), while for the other, the landmark contained four different patterns (i.e., it looked different when approached from different directions). The first group learned to swim to the platform more rapidly than the second. Experiment 2 confirmed this difference when female rats were trained in a circular pool but found that male rats learned equally rapidly (and as rapidly as females trained with the single-pattern landmark) with both landmarks. This second finding was confirmed in Experiment 3. Finally, in Experiment 4a and 4b, male and female rats were trained either with the same, single-pattern landmark on all trials or with a different landmark each day. Males learned equally rapidly (and as rapidly as females trained with the unchanged landmark) whether the landmark changed or not. We conclude that male and female rats learn rather different things about the landmark that signals the location of the platform.     

Teaching Modern Chemistry through ‘Recurrent Historical Teaching Models’

Today there are little more of 3 million chemist all over the world producing about 800,000 papers a year. They produce new substances – from some hundreds in 1800 to about 20 million now – the vast majority artificial. This rate is growing quite fast. Once the majority of chemistry teachers all over the world used textbooks as the main (sometimes the only) source of information, we became, without wanting to... history teachers! If ‘scientific literacy’ is the aim of science lessons in school, it is much more than the literacy now developed in science classrooms. It must include an understanding of the nature and process by which scientific activities are carried out. Recognition of the exponentially chemistry knowledge growth and the incompleteness of the current chemistry textbooks are thus intimately related to recognition of the need for recurrent historical teaching models.     

Inhibitory associations between neutral stimuli: A comparative approach

In Experiments 1A, 1B, and 1C, nonhuman subjects, rats, received long alternated exposures to two compound flavors, AX and BX, that shared one flavor in common, X. Following this, conditioning of an aversion to A was sufficient to establish B as a conditioned inhibitor of the aversive unconditioned stimulus, passing both summation and retardation tests. Two additional experiments (Experiments 2 and 3) expanded the generality of these results to humans, using similar designs but an auditory discrimination learning task. A set of notes sequentially presented served as cues and fictitious composers served as outcomes. Both summation and retardation effects were found (Experiments 2 and 3, respectively). Experiment 4 then sought to clarify the mechanism underlying these effects. The results are discussed within several theoretical frameworks, most centrally the McLaren, Kaye, and Mackintosh (1989) theory of perceptual learning.     

Spatial integration with rats

Rats were trained to find the hidden platform in a Morris pool, whose location was defined by reference to a small number of landmarks around the circumference of the pool. In each of three experiments, an experimental group was trained on alternate trials with two different subsets of three of the available landmarks, with the two subsets sharing one landmark in common. When tested with landmarks drawn from both of their training configurations, but without the landmark common to the two sets, they had no difficulty in locating the platform. In Experiment 1, they performed at least as well as a group trained with all the available landmarks present on every trial. In Experiment 2, they performed significantly better than a group trained with two different subsets of landmarks that shared no one landmark in common.     

Overshadowing in the spatial domain

In Experiments 1 and 2, rats were trained in a Morris water maze to locate a hidden platform, the location of which in the circular pool was defined by four visual landmarks (A, B, C, and D), spaced at equal intervals around the edge of the pool. Control animals were trained with these four visual landmarks only. But for animals in the overshadowing groups, an auditory component, X, was added to Landmark D. Test trials, given at the end of training, consisted of placing the rat in the pool with no platform present and recording the time rats spent in the platform quadrant. In Experiment 1, the overshadowing group spent less time in the platform quadrant than controls when tested with D, but the two groups performed equally well on test trials that did not use D. We conclude that the auditory Component X overshadowed the visual Landmark D. In Experiment 2, we obtained evidence of reciprocal overshadowing, of D by X and of X by D. The results of Experiment 3 suggested that an appeal to generalization decrement might not be sufficient to explain these overshadowing effects.     

Heuristic Diagrams as a Tool to Teach History of Science

The graphic organizer called here heuristic diagram as an improvement of Gowin’s Vee heuristic is proposed as a tool to teach history of science. Heuristic diagrams have the purpose of helping students (or teachers, or researchers) to understand their own research considering that asks and problem-solving are central to scientific activity. The left side originally related in Gowin’s Vee with philosophies, theories, models, laws or regularities now agrees with Toulmin’s concepts (language, models as representation techniques and application procedures). Mexican science teachers without experience in science education research used the heuristic diagram to learn about the history of chemistry considering also in the left side two different historical times: past and present. Through a semantic differential scale teachers’ attitude to the heuristic diagram was evaluated and its usefulness was demonstrated.     

A New Definition of Models and Modeling in Chemistry’s Teaching

The synthesis of new chemical compounds makes it the most productive science. Unfortunately chemistry education practice has not been driven to any great extent by research findings, philosophical positions or advances in new ways of approaching knowledge. The changes that have occurred in textbooks during the past three decades do not show any real recognition of these. Despite previously reported different types of models in this paper, from an ‘empirical reliability with minimal realism’ approach to realism, a new simple and broad definition, a typology of models and their relation with modeling is presented.     

The Role of Instruments in Three Chemical’ Revolutions

This paper attempts to show one of the ways history of chemistry can be teachable for chemistry teachers, it means something more than an undifferentiated mass of names and dates, establishing a temporal framework based on chemical entities that all students use. Represents a difficult equilibrium between over-simplification versus over-elaboration. Hence, following the initial proposal of Jensen (J Chem Educ 75:679–687, 817–828, 961–969, 1998), reconstructs the history of one of chemistry’ dimensions (composition-structure) in terms of three revolutionary moments. These moments are considered in terms of the Kuhnian notion of ‘exemplar,’ rather than ‘paradigm.’ This approach enables the incorporation of instruments, as well as concepts into the revolutionary process and provides a more adequate representation of such periods of development and consolidation. These three revolutions are called by the chemical structural entities that emerged from the same: atoms (1766–1808); molecules and isomers (1831–1860); electrons and isotopes (1897–1923).     

Overshadowing and blocking between landmark learning and shape learning: the importance of sex differences

Rats were trained in a triangular-shaped pool to find a hidden platform that maintained a constant relationship with two sources of information, an individual landmark and one part of the pool with a distinctive shape. In Experiment 1, shape learning overshadowed landmark learning but landmark learning did not overshadow shape learning in males, while landmark learning overshadowed shape learning but shape learning did not overshadow landmark learning in females. In Experiment 2, rats were pretrained either with the single landmark relevant or with the shape relevant, in the absence of the alternative cue. Final test trials, without the platform, revealed reciprocal blocking only in females; in males, shape learning blocked landmark learning, but not viceversa (Experiment 2a). In Experiment 2b, male rats received a longer pretraining with the single landmark relevant, and now landmark learning blocked shape learning. The results thus confirm the claim that males and females partially use different types of spatial information when solving spatial tasks. These results also agree with the suggestion that shape learning interacts with landmark learning in much the same way as does learning about any pair of stimuli in a Pavlovian conditioning experiment.