Perception of frequency, amplitude, and azimuth of a vibratory dipole source by the octavolateralis system of goldfish (Carassius auratus).

Goldfish (Carassius auratus) were conditioned to suppress respiration to a 40-Hz vibratory source and subsequently tested for stimulus generalization to frequency, stimulus amplitude, and position (azimuth). Animals completely failed to generalize to frequencies separated by octave intervals both lesser and greater than the CS. However, they did appear to generalize weakly to an aerial loudspeaker stimulus of the same frequency (40 Hz) after conditioning with an underwater vibratory source. Animals had a gradually decreasing amount of generalization to amplitude changes, suggesting a perceptual dimension of loudness. Animals generalized largely or completely to the same underwater source presented at a range of source azimuths. When these azimuths were presented at a transect of 3 cm, some animals did show decrements in generalization, while others did not. This suggests that although azimuth may be perceived more saliently at distances closer to a dipole source, perception of position is not immediately salient in conditioned vibratory source detection. Differential responding to test stimuli located toward the head or tail suggests the presence of perceptual differences between sources that are rostral or caudal with respect to the position of the animal or perhaps the head.

The detection of pressure fluctuations, sonic audition, is the dominant mode of dipole-source detection in goldfish (Carassius auratus).

Behavioral detection of a low-frequency (40 Hz) vibratory dipole at source distances of 1.5-24 cm was measured by classically conditioned respiratory suppression in goldfish (Carassius auratus). Detection thresholds were compared across distances and before and after ablation of individual octavolateralis sensory channels. Detection thresholds, expressed in units of pressure (SPL), remained roughly constant as distance between the stimulus source and animal increased. Lateral line inactivation, using CoCl2, had no measurable effect on sensitivity, although some other results can be construed as weak evidence for a small contribution of the lateral line to dipole detection when source distances are

Processing of conflicting and redundant stimulus information by pigeons.

Selective attention in processing of visual information by pigeons, trained on alternating sessions with two colors (red and green) and two forms (a diamond and an X shape) differentially associated with a left-right key choice task, was examined. A color and a form were presented together on probe trials during sessions in which, on other trials, only one of the dimensions, color or form, was shown. The dimension in effect on the surrounding trials had no influence on choice when the information provided by the two dimensions on probe trials was in conflict--color correct for one choice and form for the other. When both color and form redundantly cued the correct choice, there was no increase in accuracy in comparison with that associated with one dimension. Following separate training on the color and form discriminations, pigeons appeared to base their choices on color on some trials, on form on other trials, but not on both simultaneously. These findings are discussed in terms of an exemplar model of information processing.