Simultaneous color contrast in 4-month-old infants.

The present paper addresses the question of simultaneous color contrast in 4-month-old human infants. A temporal modulation paradigm was employed for infant testing. In this paradigm, infants viewed two test disks presented side-by-side: one of unchanging chromaticity (static) and another of the chromaticity varied in time (temporally modulated).

Infant color vision: infants' spontaneous color preferences are well behaved.

Stochastic transitivity (ST) is a property of preferences among pairs of objects formed from three alternatives, a, b, and c. In general, ST states that if a is preferred to b, and b is preferred to c, then a will be preferred to c. Stochastic transitivity can be weak, moderate, strong or strict (see text).

Infant color vision: prediction of infants' spontaneous color preferences.

Infants show spontaneous looking preferences among isoluminant chromatic stimuli [Adams, R. J. (1987).

Lightness constancy in 4-month-old infants.

In the present study, discrete trial familiarization/novelty techniques were used to study lightness constancy in 4-month-old infants. The test stimuli were real objects (paper smiley faces) of two different reflectances, dark gray (17% reflectance) and light gray (54% reflectance). In Experiment 1, the test stimuli were viewed against a white (90% reflectance) surround, and in Experiment 2, against a black (4.

Centering biases in heterochromatic brightness matching.

When the method of constant stimuli is used to measure heterochromatic brightness matches, the resulting matches can be strongly biased toward the center of the range of test luminances used. In the present paper, we investigate the source of this centering bias. The stimuli were 2 degrees red squares presented in a gray surround.

Achromatic contrast effects in infants: adults and 4-month-old infants show similar deviations from Wallach's ratio rule.

When adults view a disk of light embedded in a higher luminance surround, the perceived lightness of the disk is largely determined by the surround to disk luminance ratio (Wallach's ratio rule). In the present study, both adult and infant subjects were tested with multiple discrete trial procedures in which the surround luminance was decreased between the study and test phases of each trial. Tested with sequential lightness matching, adult subjects showed an approximate ratio rule, with a small but consistent deviation in the direction of a luminance match.

Relations Among Spontaneous Preferences, Familiarized Preferences, and Novelty Effects: Measurements With Forced-Choice Techniques.

We here describe a discrete trial, forced-choice, combined spontaneous preference and novelty preference technique. In this technique, spontaneous preferences and familiarized (postfamiliarization) preferences are measured with the same stimulus pairs under closely parallel conditions. A variety of systematic stimulus variations were used in 16-week-old infants to explore the interrelations among spontaneous preferences, familiarized preferences, and familiarization (novelty) effects.

Infants' spontaneous color preferences are not due to adult-like brightness variations.

In the present work, we explore the perceptual bases of infants' spontaneous looking preferences among isoluminant chromatic stimuli (Bornstein, 1975). Three experiments were conducted. In Experiment 1, adult subjects made brightness matches between a white standard and each of six isoluminant chromatic stimuli.

Infant color vision: influence of surround chromaticity on spontaneous looking preferences.

When infants are tested with stimuli of various chromaticities embedded in a dark or achromatic (white) surround, they show maximal preference for stimuli of maximal colorimetric purity, and minimal preference for achromatic stimuli. We investigated how this pattern of preferences changes with changes of surround chromaticity. Sixteen-week-old infants were tested in two experimental conditions.

Adult brightness vs. luminance as models of infant photometry: variability, biasability, and spectral characteristics for the two age groups favor the luminance model.

When infants fail to make chromatic discriminations, do the characteristics of their performance minima coincide more closely with the properties of adult luminance matches or heterochromatic brightness matches? In addition to their spectral properties, adult luminance matches are typically characterized by relatively small individual differences, whereas brightness matches are believed to be both more variable and more biasable. Two complementary experiments were carried out on adults and 8-week-old infant subjects. Both groups were tested with small (1.

Infant lightness perception: do 4-month-old infants follow Wallach's ratio rule?

When adults view a test disk embedded in a higher-luminance surround, the perceived lightness of the disk is largely determined by the surround-to-disk (S/D) luminance ratio (Wallach's ratio rule). Performance of 4-month-old infants tested with a forced-choice novelty-preference technique was consistent with predictions based on Wallach's ratio rule. This result suggests that the ability to extract and maintain information about local luminance ratios is present early in infancy.

Infant photometry: are mean adult isoluminance values a sufficient approximation to individual infant values?

Individual differences in isoluminance values were studied in infants and adults using a motion nulling paradigm. Two luminance-modulated sinusoidal grating components (spatial frequency=0.25 cpd, temporal frequency=5.