Sensitizing properties of spectral lights in 4-month-old human infants

Previous studies of infant attention, learning, and memory have revealed that certain stimulus properties may increase an infant's arousal or excitation level, thereby increasing responsiveness and facilitating the encoding and processing of information. In a series of experiments aimed at identifying stimulus determinants of sensitization, we examined visual responses from 4-month-old infants to spectral lights. Habituation data were obtained from 92 full-term infants separated into one of five groups. Each group viewed either a broadband white light (correlated color temperature approximately 2800 K) or one of four different spectral lights (lambda d = 470, 510, 570, or 650 nm) approximately corresponding to the elemental hues blue, green, yellow and red, respectively, for adults with normal trichromatic vision. Stimuli were equated in luminous efficiency for a standard infant observer. Stimulus fixation was recorded for twelve 10-s presentations, each separated by 10-s interstimulus intervals (ISIs). The results show that mean fixation times to the red and green lights were significantly greater than those for the blue and white light. Mean fixation time for the yellow light was also reduced (significantly) compared to the red but not the green light. These results suggest that the chromatic properties of red and green spectral lights may be more sensitizing to infants than those of the blue, yellow, or white lights.