Louise Hainline

Developmental changes in visual scanning of face and nonface patterns by infants.

Abstract The eye movements of infants, aged 4–5, 7–8, and 10–11 weeks, were recorded while they viewed either a representation of a face or a nonface stimulus. Presentation of the visual stimulus was paired with the presentation of an auditory stimulus (either voice or tone) or silence. Attention to the visual stimulus was greater for the older two groups than for the youngest group. The effect of the addition of sound was to increase attention to the visual stimulus. In general, the face was looked at more than the nonface stimulus. The difference in visual attention between the face and the nonface stimulus did not appear to be based solely on the physical characteristics of the stimuli. A sharp increase in the amount of looking at the eyes of the face stimulus at 7–8 weeks of age seemed to be related to a developing appreciation of the meaning of the face as a pattern.

Characteristics of saccades in human infants

Infants (14-151 days) and adults were shown two-dimensional geometric forms or stimuli from a set of highly textured patterns. Their eye movements were recorded by an infrared corneal reflection eye movement recorder as they freely scanned the stimuli. For both infants and adults, linear relationships were found between the peak velocities of fast eye movements and their amplitudes (main sequences). Infants viewing texture stimuli had main sequences with slopes comparable to those of adults. Infants viewing simple geometric forms made slower saccades. They also showed more eye movement oscillations which analyses showed were probably back-to-back saccades. Both the slower saccades and saccadic oscillations were attributed to factors related to the attentional value of the stimuli.

The distribution of fixation durations in infants and naive adults

The distributions of durations of fixations from infants and free-viewing adults are shown to be basically exponential for different stimulus conditions. It is found that fixation duration can be divided into two periods. One, the alpha-period, is a refractory period during which a saccade does not occur and fluctuates across fixations. The other, the beta-period, is a random variable intrinsic to each fixation and constitutes a waiting-time for a saccade that occurs with constant probability per unit time. It is shown that mean duration decreases when stimulus size increases. These results suggest that fixations are terminated by saccades triggered by non-foveal stimulation.

Development of accommodation and convergence in infancy

Paraxial photorefraction was used to assess the development of accommodation and convergence in a large sample of infants under 1 year of age. The infants viewed small dolls placed at various distances (200-25 cm). The majority of infants at all ages demonstrated appropriate convergence for target distance, regardless of manifest refractive error. However, accommodation lagged behind convergence in development. Infants under 2 months tended to demonstrate either flat accommodation responses with a fixed plane of focus at around 30 cm, or accommodated appropriately for near targets, but failed to relax their accommodation sufficiently for the more distant targets. Thus, the focussing error increased with increasing target distance. Since the manifest refractive error was estimated by extrapolating the accommodation function to 0 diopters demand, these infants demonstrated spuriously myopic behavior. After 2 months, the majority of infants showing emmetropic behavior had accommodation responses that changed appropriately with target distance. However, infants with myopic or hyperopic manifest refractive errors displayed a variety of accommodative styles.

Comparison of Measures of Visual Acuity in Infants: Teller Acuity Cards and Sweep Visual Evoked Potentials

Purpose: This study compares the development of acuity in the same infants during one testing session using Teller acuity cards (TAC) and sweep visual evoked potentials (sVEP). We asked whether different testing methods in two centers would produce different developmental time courses. Methods: Forty-eight infants were tested in two centers. The standard procedure for TAC was used. For sVEP acuity, the amplitude response curve derived from time-locked cortical activity was used to extrapolate to zero response, giving an acuity estimate for each infant. Results: sVJEP acuity was generally higher than TAC acuity. The rate of development was steeper for TAC than sVEP acuity with TAC starting at a much lower level. The ratio of sVEP to TAC acuity decreased exponentially with age reaching an asymptote of about 1.44 at 6 months. Conclusions: Results were indistinguishable between centers suggesting that comparison of acuity measures obtained using variations of these methods across centers is possible.

Binocular alignment and vergence in early infancy

Vergence to static targets presented at five distances between 25 and 200 cm from the subject was measured in 631 infants aged between 17 and 120 days. Photographic images of the eyes were magnified and measured to yield information on the monocular and binocular eye positions for each target. Vergence data were fit by a linear function and compared to the vergence calculated from target distance and each infants measured interpupillary distance. Differences in vergence across targets were also evaluated for each subject by calculating the change in angle of rotation for each eye. Many of even the youngest infants showed good ocular alignment both monocularly and binocularly, although the youngest infants showed the greatest variability in vergence. However, the median difference in vergence angle between the eyes for even the youngest group was < 4 deg (6.8 prism D), and some of this difference is attributed to versional eye movements and to slightly off-axis head position across trials. The average infant of 1-2 months showed substantially better vergence than has been reported in some recent studies. Apparently, oculomotor constraints are not a significant barrier to the development of the higher forms of binocularity that begin to emerge in the months immediately following the interval studied here, and may form the substrate for later developments in binocular vision.

An automated eye movement recording system for use with human infants

An infrared corneal reflection eye movement system modified for work with human infants is described. The system generates on-line digital information on eye position at a sampling rate that allows examination of the temporal and spatial characteristics of fixations and eye move-ments. An algorithm for defining fixation and eye movement episodes is described.

A method for calibrating an eye-monitoring system for use with infants

An algorithm for calibrating data from an infrared corneal reflection eye movement monitor is described. The algorithm is designed for use with infants and other noninstructable subjects.

The Correlates of Childhood Father Absence in College-aged Women.

HAINLINE, LOUISE, and FEIG, ELLEN. The Correlates of Childhood Father Absence in Collegeaged Women. CHILD DEVELOPMENT, 1978, 49, 37-42. The correlates of father absence early (before age 5) or late (between 5 and 11) in childhood were studied in a sample of college-aged women; father absence was due to either death or divorce. In comparison to father-present controls the father-absent subjects showed few deviations in such personality measures as degree of sex-role typing, attitudes toward romantic love, sex-role traditionalism, manifest anxiety, or locus of control. There did appear to be some attitudinal differences about the acceptability of sexual intercourse for the father-absent groups, but there were no differences in the amount of heterosexual behaviors actually reported. The father-absent subjects did not differ from the controls on various measures of nonverbal behavior to male interviewers. Reasons for the lack of agreement with a study by E. M. Hetherington are discussed; the primary factors of relevance seem to be age of the subjects at testing, SES, race, ethnicity, education, and family composition.

The effect of colored lenses on the visual evoked response in children with visual stress

Purpose. Some children with visual stress and/or headaches have fewer symptoms when wearing colored lenses. Although subjective reports of improved perception exist, few objective correlates of these effects have been established. Methods. In a pilot study, 10 children who wore Intuitive Colorimeter lenses, and claimed benefit, and two asymptomatic children were tested. Steady-state potentials were measured in response to low contrast patterns modulating at a frequency of 12 Hz. Four viewing conditions were compared: 1) no lens; 2) Colorimeter lens; 3) lens of complementary color; and 4) spectrally neutral lens with similar photopic transmission. Results. The asymptomatic children showed little or no difference between the lens and no lens conditions. When all the symptomatic children were tested together, a similar result was found. However, when the symptomatic children were divided into two groups depending on their symptoms, an interaction emerged. Children with visual stress but no headaches showed the largest amplitude visual evoked potential response in the no lens condition, whereas those children whose symptoms included severe headaches or migraine showed the largest amplitude visual evoked potential response when wearing their prescribed lens. Conclusions. The results suggest that it is possible to measure objective correlates of the beneficial subjective perceptual effects of colored lenses, at least in some children who have a history of migraine or severe headaches.