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PubMed1991

Generalized discrimination of positive facial expression by seven- and ten-month-old infants.

The ability of 7- and 10-month-old infants to generalize their discrimination of facial expressions lacking featural consistency was investigated in a series of 4 experiments. Infants were habituated to models posing either prototypically positive displays (e.g., happy expressions) or positive expression blends (e.g., mock surprise). They were then tested for their ability to recognize a positive expression on the face of a novel model and to discriminate positive and negative facial expressions. Only in Experiment 1, in which infants were familiarized to a mix of happy and surprised facial expressions, did 10-month-olds demonstrate generalized discrimination of positive affect. When positive blends or happy expressions alone served as familiarization stimuli, both 7- and 10-month-old infants failed to dishabituate to a change in affective tone. 7-month-olds, in particular, showed consistent recovery of looking to the introduction of novel models. The pattern of results suggests that it is not until sometime after 7 months of age that dependence on the presence of expression-specific features for affect recognition and discrimination diminishes. By 10 months of age, however, infants are beginning to recognize the affective similarity of familiar positive facial expressions.

Affect↗
PubMedDate not supplied

[The capacity of bottle-nosed dolphins for generalization according to a relative sign].

In bottle-nosed dolphins by a new modification of previously suggested method, a conditioned reflex was elaborated and consolidated to a relative spatial sign--choice of always left object from two similar ones in conditions of a permanent change of place of this pair of stimuli against the background of one of the sides of an open-air cage. Specialization of the reflex was checked by presentation of a pair of stimuli under different changes of surroundings, including discordance of external orientors and also the way of stimuli presentation. Then the initial objects were substituted by others (12 pairs of stimuli) sharply differing from the initial ones by the form, size, material etc. Retention of adequate choice also at the change of the medium of stimuli presentation, testified to the ability of dolphins of abstraction and generalization by relative sign, i.e. at the choice from two objects of the type "to the right--to the left in general".

Animals↗
PubMed1989

What makes a vibble a vibble? A developmental study of category generalization.

Young children appear to know when a novel label for a novel object is a common noun. The present study was concerned with the properties of a named object that children assume to be true of other members of the category that is specified by such a noun. Preschoolers, second graders, and college students were shown drawings of objects and given nonsense labels for those objects. They then viewed other objects that varied from the labeled ones along 4 particular attributes and were asked to decide if those other objects should also receive the same label. Preschoolers focused mostly on single attributes in making category decisions, and their choices of attributes were evenly distributed among the 4 types. Older individuals primarily exhibited multiple attribute rules. The results are discussed in terms of developmental differences in the modes of processing that are used and in the types of knowledge that are brought to bear on the word learning situation.

Attention↗
PubMed1989

Acquired equivalence and distinctiveness of cues.

In Experiments 1 and 2, rats received initial training in which two stimuli (A and N) were either followed by the same consequence (food) or by different consequences (food and no food). Subsequently N was paired with electric shock and the generalization of conditioned suppression to A was assessed. Suppression to A was more marked when A and N had both been followed by food than when they had had different outcomes. In Experiment 3, 3 stimuli (A, B, and N) were presented initially. For one group, A and N were paired with food and B was nonreinforced: for a second group, B was paired with food and A and N were nonreinforced. Generalization of suppression was found to be more substantial to A than to B for both groups. These results indicate that the extent to which stimuli are treated as being equivalent is partly determined by their reinforcement histories.

Animals↗
PubMedDate not supplied

[Neuropharmacologic analysis of the process of generalization in the cat].

Processes of generalization and abstraction were studied in intact cats before and after systemic administration of dopamine-, cholin- and GABA-ergic substances in conditions of free behaviour with food reinforcement by a developed method. It is shown that only inhibition or activation of dopaminergic system disturbs the function of generalization in animals. Some possible neurochemical mechanisms of generalization in animals are being analyzed.

Animals↗
PubMed1988

Functional anatomy of macaque striate cortex. I. Ocular dominance, binocular interactions, and baseline conditions.

A series of experiments was carried out using 14C-2-deoxy-d-glucose (DG) in order to examine the functional architecture of macaque striate (primary visual) cortex. This paper describes the results of experiments on uptake during various baseline (or reference) conditions of visual stimulation (described below), and on differences in the functional architecture following monocular versus binocular viewing conditions. In binocular "baseline" experiments, monkeys were stimulated either (1) in the dark, (2) with a diffuse gray screen, or (3) with a very general visual stimulus composed of gratings of varied orientation and spatial frequency. In all of these conditions, DG uptake was found to be topographically uniform within all layers of parafoveal striate cortex. In monocular experiments that were otherwise similar, uptake was topographically uniform within the full extent of the eye dominance strip, in all layers. Certain other visual stimuli produce high uptake in the blobs, and still another set of visual stimuli (including high-spatial-frequency gratings) produce highest uptake between the blobs at parafoveal eccentricities, even in an unanesthetized, unparalyzed monkey. Eye movements per se had no obvious effect on striate DG uptake. Endogenous uptake in the blobs (relative to that in the interblobs) appears higher in the squirrel monkey than in the macaque. The pattern of DG uptake produced by binocular viewing was found to deviate in a number of ways from that expected by linearly summing the component monocular DG patterns. One of the most interesting deviations was an enhancement of the representation of visual field borders between stimuli differing from each other in texture, orientation, direction, etc. This "border enhancement" was confined to striate layers 1-3 (not appearing in any of the striate input layers), and it only appeared following binocular, but not monocular, viewing conditions. The border enhancement may be related to a suppression of DG uptake that occurs during binocular viewing conditions in layers 2 + 3 (and perhaps layers 1 and 4B), but not in layers 4Ca, 4Cb, 5 or 6. Another major class of binocular interaction was a spread of neural activity into the "unstimulated" ocular dominance strips following monocular stimulation. Such an effect was prominent in striate layer 4Ca, but it did not occur in layer 4Cb. This "binocular" spread of DG uptake into the inappropriate eye dominance strip in 4Ca may be related to the appearance of orientation tuning and orientation columns in that layer. No DG effects were seen that depended on the absolute disparity of visual stimuli in macaque striate cortex.

Animals↗
PubMed1987

[Formation of a generalized reaction of choice of object according to color in a young chimpanzee].

It has been established that the necessary conditions for rapid formation of experience in chimpanzees are creation of the interspecific functional system experimenter-chimpanzee in which the mechanisms of imitation and refreshment and creation of situational conditional reflex may be equally used. The neurophysiological basis of the latter is the stage activity when each stage is the signal for the following and refreshment for the previous one. In the presence of these factors the possibility of formation of aim generalized reflex appears, that is the basis for creation of optimum conditions for perception and learning the given information.

Animals↗
PubMed1986

Categorical shape and color coding by pigeons.

Categorical coding is the tendency to respond similarly to discriminated stimuli. Past research indicates that pigeons can categorize colors according to at least three spectral regions. Two present experiments assessed the categorical coding of shapes and the existence of a higher order color category (all colors). Pigeons were trained on two independent tasks (matching-to-sample, and oddity-from-sample). One task involved red and a plus sign, the other a circle and green. On test trials one of the two comparison stimuli from one task was replaced by one of the stimuli from the other task. Differential performance based on which of the two stimuli from the other task was introduced suggested categorical coding rules. In Experiment 1 evidence for the categorical coding of sample shapes was found. Categorical color coding was also found; however, it was the comparison stimuli rather than the samples that were categorically coded. Experiment 2 replicated the categorical shape sample effect and ruled out the possibility that the particular colors used were responsible for the categorical coding of comparison stimuli. Overall, the results indicate that pigeons can develop categorical rules involving shapes and colors and that the color categories can be hierarchical.

Animals↗
PubMed1986

[Intelligence training of handicapped patients. An experimental evaluation study of constructive training for the promotion of general intelligence in learning disabled students in a school for patients with speech disorders].

Starting out from a curricular analysis of Klauer's "G-V"-tree structure (1984), a training scheme for developing central intellectual performance is set out and evaluated. The training consists of operations to determine sameness (G = Gleichheit) or differentness (V = Verschiedenheit) of features or relationships. As suggested by the theory of the G-V algorithm, and after only four training units of 45 minutes each, significant gains in general intelligence were found in the two training groups of slow learning students from a special school for the speech disordered, gains that the two control groups did not demonstrate. Meichenbaum's cognitive modelling with subsequent verbal self-instruction served to facilitate task solution procedures. The findings are discussed within the theoretical framework of the G-V system, emphasizing in particular its relevance for modifying and enhancing information processing functions in learning disabled students.

Child↗
PubMed1985

Accommodation for flickering stimuli.

A laser optometer was used to measure accommodative responses of three observers for sinusoidal gratings presented in Maxwellian view at optical distances ranging from 0 to 4 diopters. Contrast of the stimuli was modulated spatially at 1.0, 4.2 and 6.5 cycles deg.-1 (cpd), and temporally at six frequencies ranging from 3.0 to 40 Hz. Accommodation was consistently more accurate for the 4.2 cpd than for either the 1.0 or 6.5 cpd gratings. Furthermore, accommodative responsiveness for the 4.2 cpd was not affected by temporal modulation, while that for the other spatial frequencies improved monotonically as a function of temporal frequency. These results reinforce earlier reports that accommodation is most responsive for contrast of intermediate spatial frequencies and they indicate that stimulus flicker generally degrades accommodation for spatial contrast.

Accommodation, Ocular↗