Marie Balaban - US grants

The mature human visual system, adept at detecting dynamic sensory events, often shifts attention automatically toward a detected movement or change in the environment. There are many studies of the maturation in infants of spatial aspects of vision, such as acuity and preferences for various stationary patterns, but fewer studies of the temporal characteristics of infant vision. Yet the infant, from an early age, encounters a dynamic sensory world. This research will examine the development of infants' visual sensitivity to temporal changes. The initial goal is to assess infant preferences for flashing displays by presenting two patterns flickering at different rates. The research will use measures of the time infants spend looking at each pattern, along with physiological measures of their eye movements and heart rate, to assess preferences and thus infer temporal sensitivity. Further studies will investigate the cueing effects of flashing or moving stimuli presented in the periphery of the visual field. Although infants can localize lights and sounds coarsely soon after birth, these abilities become greatly refined during early infancy. The third goal is to use the attention-attracting nature of stimulus change as a probe of infant attention. The question is how readily abrupt changes in the visual periphery will distract infants' viewing of centrally-presented stimuli. Initial activities will include selection of suitable stimuli for infants of different ages and pilot work on precise measurement of shifts in visual fixation. This research will study infants from 2 through 6 months of age, spanning the period during which temporal acuity in the visual system is undergoing rapid developmental change. The research will address both the development of the visual system and the implications of more temporally-refined visual processing for the infant's attention to their surroundings. Maturation of the ability to detect change, to localize the source of the change, and to focus attention to the sensory event is necessary for developing competence in interaction with persons and objects in the environment.

The proposed research examines the early development of physiological and behavioral reactivity to emotionally-salient events during infancy. Convergent methodologies from studies of fear-potentiation of startle in animals and studies of affective modulation of blink reflex responses in human adults are adapted in order to investigate the emergence of infants' sensitivity to affective information conveyed by emotional expression. The methods employ a sudden brief acoustic noiseburst as a physiological probe" of the infant's affective state during the viewing of emotionally expressive faces. Like adults, 5-month-old infants show potentiated reflex responses during negative, relative to positive and neutral, affective displays. The proposed research incorporates three areas of inquiry. The first cross-sectional project delineates the development of affective reflex modulation during early infancy. Developmental comparison of changes in reflex size and speed with changes in overt behavioral responses will determine whether physiological responsivity to affective valence precedes or coincides with behavioral reactivity. The second objective is to discover whether infants, like adults, demonstrate right-hemisphere lateralization of affective signal processing. The startle blink paradigm is well-suited for the study of laterality effects because it allows comparison of how responses to left-ear and right-ear acoustic probes are influenced by the presentation of affective expressions. The final project assesses individual differences in sensitivity to affective modulation. Infants who are highly reactive to unfamiliar sensory events may also show greater potentiation of reflex activity during negative affective displays. This finding would link stable individual differences in behavioral inhibition, demonstrated in human infants and children, with an anatomically distinct pathway for fear modulation, demonstrated in animals. The proposed research is expected to clarify mechanisms involved in the perception of emotional signals and the regulation of emotional responses; both are integral processes in early psychological development.

The proposed research examines the early development of physiological and behavioral reactivity to emotionally-salient events during infancy. Convergent methodologies from studies of fear-potentiation of startle in animals and studies of affective modulation of blink reflex responses in human adults are adapted in order to investigate the emergence of infants' sensitivity to affective information conveyed by emotional expression. The methods employ a sudden brief acoustic noiseburst as a physiological probe" of the infant's affective state during the viewing of emotionally expressive faces. Like adults, 5-month-old infants show potentiated reflex responses during negative, relative to positive and neutral, affective displays. The proposed research incorporates three areas of inquiry. The first cross-sectional project delineates the development of affective reflex modulation during early infancy. Developmental comparison of changes in reflex size and speed with changes in overt behavioral responses will determine whether physiological responsivity to affective valence precedes or coincides with behavioral reactivity. The second objective is to discover whether infants, like adults, demonstrate right-hemisphere lateralization of affective signal processing. The startle blink paradigm is well-suited for the study of laterality effects because it allows comparison of how responses to left-ear and right-ear acoustic probes are influenced by the presentation of affective expressions. The final project assesses individual differences in sensitivity to affective modulation. Infants who are highly reactive to unfamiliar sensory events may also show greater potentiation of reflex activity during negative affective displays. This finding would link stable individual differences in behavioral inhibition, demonstrated in human infants and children, with an anatomically distinct pathway for fear modulation, demonstrated in animals. The proposed research is expected to clarify mechanisms involved in the perception of emotional signals and the regulation of emotional responses; both are integral processes in early psychological development.