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Eleven generations of bidirectionally selecting quail (C. coturnix japonica) for nonspecific imprintability to blue or red stimuli resulted in unexpectedly slow yet reliable differentiation of "Hi" and "Lo" imprintability lines. Correlated changes were observed in the variances of unconditional color choices in subjects belonging to these genetic lines. Implications of the data for understanding the interrelated expression of gene effects and environment effects in the development of behavior are discussed.

Visual preferences were studied in 18,225 quail chicks (Coturnix coturnix japonica) of three genetic populations, in relation to 185 pairs of systematically varied and combined flash rates, flash amplitudes, luminances, and colors. Results indicate additive and nonadditive interactions between preference values of stimulus elements embedded in complex stimulus information. Flicker preferences changed with changes in overall stimulus liminances, flash amplitudes, and colors. Likewise, color preferences changed with the presence or absence and rate of flicker. Interactions between preference values of stimuli were related to threshold effects and genetic influences. Dominance of flicker over color preference was found in genetic controls, but subjects drawn from the 14th generation of bidirectional genetic selection for color choices preferred the genetically favored colors regardless of flicker. Discussion examines the data from the perspectives of coding and processing stimulus information.

Genetic analysis of approach preferences for blue and red colors in 1-day-old, experientially naïve quail, at 12th through 14th generations of bidirectional genetic selection, implicate four to eight segregating units of inheritance. Because the quails' initial approach choices are also readily modifiable by experience, these results point the way to studying the mediation of gene effects, environment effects, and gene-environment interactions in visually guided behaviors.

Approach choices were tested in genetically and environmentally manipulated quail chicks with pairs of stimuli identical in size and luminance but different in color, flicker, or both color and flicker. Data indicated comparable flicker and vastly different color preferences in subjects that were bidirectionally selected for color choices. In the choices between composite stimuli, flicker effects dominated over color effects in genetic controls, and color effects over flicker effects in selected subjects. Imprinting to colors modified color preferences, but imprinting to white or colored flicker did not change, or only marginally changed, flicker preferences. Flicker in testing stimuli, however, influenced the phenotypic expression of acquired color preferences. The data are examined for implications about the nature of constitutional biases and constitution--environment interactions in early perception and perceptual learning.

A new method for obtaining bipolar electroencephalographic (EEG) recordings from day-old Japanese quail (Coturnix coturnix japonica) is described. The electrodes are chronically placed stainless steel suture wires sewn into the skull and secured with dental acrylic. Using this arrangement, recordings were made over the hyperstriatum accessorum and dorsoarchistriatum regions of the brain. These records showed a preponderance of high amplitude slow waves. Transitions to low amplitude fast waves were also evident, and rare instances of paradoxical sleep were noted. computerized frequency analyses of the recordings divided wave numbers into distinct groups over the 1 to 17 Hz range: 1 to 4 Hz, 4 to 8 Hz, 8 to 13 Hz, and 13 to 17 Hz. Frequencies of waves detectable across the hyperstriatum accessorum were primarily confined to the 1 to 7 Hz range, whereas waves generated around the dorsoarchistriatus showed more abundant high frequency patterns. Mean amplitude of the waves (10 to 50 muV) showed an inverse exponential relationship with frequency. The method described produced an EEG of good quality on unanesthetized birds with the electrode placement procedures requiring less than 30 min.

Color preferences and preference generalization were tested in naive and imprinted Japanese quail chicks drawn from the 20th generation of a genetic control line and two genetic lines that were bidirectionally selected for preferences between blue and red. Twelve hours of imprinting to blue or red on the first posthatch day resulted in large preference changes in the genetic controls, and these subjects exhibited no or only small additional changes from 3 more days of imprinting (for the total of 66 hr of exposure time). By contrast, 12 hr of imprinting of artificially selected subjects did not change or only marginally changed their genetically manipulated preferences, but 66 hr of imprinting changed them by magnitudes as large as or larger than those in genetic controls. Reciprocal imprinting partially mimicked the phenotypic effects of bidirectional selection. Differences between transfer and generalization of phenotypically similar but genetically and experimentally different preferences indicated dissimilar mediation of the implicit gene effects and learning effects.

The hypothesis that the pigmentation of retinal oil droplets is the morphological target of genetically induced change in the early color preferences of the Japanese quail (C. coturnix japonica) was examined and rejected. Subjects were drawn from the fourth generation of genetic selection for preferences between blue and red, and they were compared according to genetic lines of origin and the presence or absence of pigmentation in their retinal oil droplets. Pigmentation was manipulated by raising parents on carotenoid-free diet. Results indicate a uniform shift toward red preference in all subjects with history of carotenoid deprivation regardless of genetic background, and no change in the magnitude of differences between genetic lines. The data suggest that retinal oil droplets mediate intensity discrimination in the photopic range rather than the perception of variations in light wavelength.

Individual variations in repeated approach choices between colors by quail chicks were efficiently and reliably identified by methods of binary mass screening and binomial assessment. Choices between a pair of identical white stimuli showed only random variations, which indicated that position habit, systematic alternation, and extraneous stimulus factors did not influence performances. Choices between blue and red colors showed significant individual variations, which were free of influences from changes in the probabilities of choices on repeated trials, interdependence between trials, and interdependence between individual performances of mass-screened subjects. Genetic determination of individual variations were shown by strong responses to bidirectional genetic selection of choices between blue and red, which also introduced small social interaction effects in mass-screened performances. Results are discussed in relation to the use of binomial distribution for identifying phenotypic units and variations in choice behaviors.

Visually-elicited early approach-behaviour was studied in 1013 Japanese quail chicks (Coturnix coturnix japonica) by a newly developed, binary assessment procedure. This procedure was shown to be highly effective for identifying approach preferences and related indivisual differences in early approach-behaviour. Experimental results show that quail chicks exhibit approach-responses to a flashing light. Within various paired intensity-combinations of the tested intensity-range of approximately two log units, they consistently preferred the higher intensity stimulus.

Bidirectional genetic selection of quail for early color preferences, for eighteen generations, resulted in nearly perfect choices of blue over red in one and red over blue in the other selected line. It also enhanced the preference of a grated over a dotted black-and-white pattern. Color and pattern preferences in hybrids of selected and control lines fell back to about halfway between parental values. Choices between composite stimuli of colors and patterns indicated summation of the respective, genetically influenced preference values, with partial dominance of color over pattern effects. Exposure to colors modified color choices. Exposure to colored patterns likewise modified color choices, but it did not change, or only marginally changed, choices between patterns. The phenotypic expression of this selective learning, however, was influenced by the genetically manipulated preference values and preference combinations of colors and patterns in the stimuli with which postexposure performances were tested. Overall, the data highlighted the need for concepts that would discriminate between the developmental and the episodic expression of genetic influences and genotype--environment interactions in behavior.