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E G Heinemann

Publications and source records attributed to E G Heinemann.

10 recordsLinked to original sources
PubMed1995

A quantitative model for simultaneous brightness induction.

The brightness that results from stimulating a particular test-region of the retina may be depressed or enhanced by simultaneous stimulation of other "inducing"-regions. The test-region brightness may be affected by contiguous inducing-regions (local contrast effects), and by non-contiguous inducing regions (long-range effects sometimes called "assimilation"). We describe a computational model for early vision that can predict the results of brightness-matching procedures commonly used to measure these phenomena. According to this model, brightness depression reflects primarily lateral inhibition that underlies local contrast effects; whereas brightness enhancement results from processes similar, in spirit, to those described in Helson's adaptation-level theory.

Contrast Sensitivity↗
PubMed1994

Context effects in visual pattern recognition by pigeons.

In the experiments described in this paper we examined the effects of contextual stimuli on pigeons' recognition of visual patterns. Experiment 1 showed a context-superiority effect. Specifically, two target forms that were identical except for location in the visual field were not discriminated when presented alone, but the compounds formed when each of these targets was placed between a nearby pair of flanking stimuli were readily discriminated. The size of the context-superiority effect decreased with increasing target-flanker separation. In Experiments 2 and 3 the two targets differed in form rather than spatial location and were readily discriminated in the absence of flankers. Under these circumstances, adding an identical pair of flankers to each target resulted in a context-inferiority effect; this is, the two target-plus-flankers compounds were less readily discriminated than the targets alone. The size of the context-inferiority effect decreased with increasing target-flanker separation. The observed effects of context are predictable from the Heinemann-Chase (1990) model of pattern recognition.

Animals↗
PubMed1993

The object-line inferiority effect in pigeons.

Eight pigeons (Columba livia) were trained to discriminate between diagonal lines presented alone or embedded in a redundant L-shape right-angle form. The stimuli were white and were presented in an environment that was otherwise totally dark. Numerous experiments done with human observers have shown a strong superiority effect when the diagonal lines are embedded in redundant contexts. However, in Experiment 1 of the present study, the pigeons discriminated significantly better between the two diagonal lines when presented alone than when they were embedded in the right-angle context. In order to check on the possibility that these results were restricted to the semi-Ganzfeld condition of Experiment 1, a second experiment was done with black stimuli presented on a white background. Results of Experiment 2 also showed a strong distractor effect. The results of the present experiments confirmed the predictions of the Heinemann and Chase model of pattern recognition by pigeons.

Animals↗
PubMed1981

Retroactive interference in discrimination learning.

In stage 1 of this experiment pigeons were trained to discriminate between two levels of noise or two colors by pecking on one of two disks. In stage 2 the discriminative stimuli were not presented, but pecking on the disks was rewarded on a random schedule. The second procedure caused the pigeons to forget the discrimination they had learned.

Acoustic Stimulation↗
PubMed1973

On the development of stimulus control.

Pigeons were trained to peck one key when presented with white noise at any of five intensities lower than a reference intensity, and to peck another key when presented with white noise at any of five intensities greater than the reference intensity. The shape of the stimulus control curves (proportion of responses to one key versus stimulus intensity) changed from a horizontal line at the beginning of training to the sigmoid form of typical psychometric functions at the end of training. The development of stimulus control is described in terms of a model based on the theory of signal recognition and a concept of attention.

Acoustic Stimulation↗
PubMed1968

Discriminative control of "attention".

Three pigeons were trained to discriminate between two tones differing in frequency in the presence of light of one color (A), and not to discriminate between the tones in the presence of light of another color (B). Generalization functions that were determined in the presence of light A showed control of behavior by the frequency of the tone; those determined in the presence of light B did not.

Animals↗