Darwin W. Muir

Social Competence and Person-Object Differentiation: An Analysis of the Still-Face Effect.

The communicative abilities of infants, revealed in the still-face (SF) procedure, were examined in 2 studies comparing behavior toward people and «interactive» objects. In Experiment 1, thirty-two 3- and 6-month-olds were presented with an object and a person (mother or female stranger). The SF effect was produced only by mothers and strangers. Positive affect clearly established person-object differentiation; infants smiled at people but rarely at the object. In Experiment 2, twelve 3-month-olds were presented with 4 stimuli: a female stranger and 3 objects with features varying in similarity to an abstract, smiling face. Again, infants reseerved their smiles for the person

Intrauterine growth retardation: a study of long-term morbidity.

Reported is the second phase of a prospective follow-up study of 76 growth-retarded children who were mature at birth and a control group of 88 children who had weights appropriate for gestational age at birth. Follow-up assessments of motor, cognitive, and language development were made between 1 and 6 years of age. The children of the intrauterine growth retardation (IUGR) group continued to be smaller than the children of the control group between 12 and 60 months of age. There was no significant difference in the incidences of motor and cognitive handicap or developmental delay, language developmental delay, and tests of vision and hearing between the children of the IUGR group and the children of the control group. There was no significant differences in performance in senior kindergarten between the children of the IUGR group and those of the control group. There was a significant relationship between the socioeconomic status, as measured by the Blishen score at birth, and the subsequent occurrence of motor and cognitive deficits.

Motor and cognitive deficits after intrapartum asphyxia in the mature fetus

The incidence of major and minor motor and/or cognitive deficits at 1 year of age, in 37 mature children who had experienced an intrapartum fetal asphyxial insult, was compared with the incidence of deficits at 1 year in 76 children of the control group. The incidence of both major and minor deficits was significantly greater in the group with intrapartum fetal asphyxia in relation to the control group. These findings support the concept that, beyond a critical threshold of fetal asphyxia, a continuum of casualty in the surviving newborn infants exists.

Factors associated with motor and cognitive deficits in children after intrapartum fetal hypoxia

Sixty children with biochemical evidence of intrapartum fetal hypoxia were studied to define the factors which distinguish the children with deficits from those without deficits of motor and cognitive development. Follow-up assessment included growth measures, neurological examination, Bayley Scales of Infant Development, and a modified Uzgiris and Hunt Scale. Eight children (13%) had a major deficit and 10 children (16%) had a minor deficit at 1 year. Children with deficits had an episode of hypoxia that was more severe and prolonged and, subsequent to delivery, a greater incidence of severe respiratory complications, apnea, and newborn encephalopathy. No other significant risk factors were identified. It is concluded that an episode of hypoxia less than one hour may occur without subsequent deficits. However, an episode of hypoxia in excess of 1 hour resulting in a metabolic acidosis of the order of 25 mEq/L will be followed by motor and cognitive deficits in approximately 50% of children.

Intrauterine growth retardation: a preliminary report of long-term morbidity.

This is a preliminary report of a prospective follow-up study of 88 intrauterine growth-retarded (IUGR) babies and a control group of 97 babies with weights appropriate for gestational age. The characteristic clinical features of IUGR pregnancies were observed in the obstetric patients of the IUGR group. The babies of the IUGR group have a phase of accelerated growth during the 3 months following delivery although they continue to be smaller than the babies of the control group at 12 months of age. No major neurologic abnormalities have been noted in the IUGR babies although behavioral differences were observed during the neonatal period and at 12 months of age. There were lower mental and physical development indices at 12 months of age which were due to the IUGR babies of lowest birth weight and those with a low maternal urinary estrogen index.

Infant Sensitivity to Perturbations in Adult Facial, Vocal, Tactile, and Contingent Stimulation During Face-to-Face Interactions

Results from studies using the Still-Face procedure showed that 3–6-month-olds respond to dynamic faces in face-to-face interactions, but not to changes in adult voice, touch or contingency in both live and televised interactions. Infant visual attention distinguished between normal and still-face periods, while smiling distinguished people from objects, and upright from inverted faces. Results from other paradigms showed that the adult voice and touch can affect infant responding and infants are sensitive to contingency. A complete description of infant’s perceptual capacities requires the use of multiple response measures and consideration of the experimental demands.

Human fetal and subsequent newborn responses to sound and vibration

Abstract Changes in human fetal heart rate and movement responses elicited by a complex noise, a 2000-Hz tone, and a vibroacoustic stimulus were examined in 36 full-term healthy human fetuses. Subsequently, 30 of the subjects were retested at 1 to 4 days of age. At each testing, each subject received a series of 8 repeating, 2 novel, and 2 re-presented stimulus trials with one of the three stimuli as well as a series of 12 control trials. Before and after birth, the magnitude of responses elicited by a noise and vibrator was substantially greater than that elicited by a tone. Responses elicited by a tone could not be differentiated from spontaneous activity occurring on control trials. This similarity in responding suggests a continuity in pre- and postnatal responding to the same kinds of stimulus materials. Furthermore, in support of a habituation explanation of response decrement, fetal cardiac acceleration and fetal movement responses declined over repeating noise trials and showed recovery on subsequent novelty (i.e., vibroacoustic) trials. Also, recovery of the fetal cardiac acceleration response (classic dishabituation) was observed on the first re-presented noise trial. Response decrement was not observed using the vibroacoustic stimulus. The demonstration of response decline, novelty response, and dishabituation to an airborne sound stimulus using this method illustrates its potential for measuring central nervous system functioning and for distinguishing between selective receptor adaptation and retention of memory models of habituation in the fetus. However, the usefulness of a habituation/dishabituation technique to study auditory processing across the pre- and postnatal periods awaits the establishment of methodological adaptations which ensure stimulus-response equivalence during fetal and neonatal testing.

Infants' Orientation to Lateral Sounds from Birth to Three Months.

Head turning to off-centered sound was videotaped monthly in a group of infants during their first 3 months of life. Infants turned reliably toward the sound at birth and at 1 and 3 months of age. They failed to respond reliably at 2 months due to an increase in no-turn responses. Potential explanations for the temporary decline in orientation responses to sound are discussed.

CULTURAL DISPLAY RULES DRIVE EYE GAZE DURING THINKING

The authors measured the eye gaze displays of Canadian, Trinidadian, and Japanese participants as they answered questions for which they either knew, or had to derive, the answers. When they knew the answers, Trinidadians maintained the most eye contact, whereas Japanese maintained the least. When thinking about the answers to questions, Canadians and Trinidadians looked up, whereas Japanese looked down. Thus, for humans, gaze displays while thinking are at least in part culturally determined.

Reaching in very young infants.

It has been claimed that reaching to visually presented targets is a valid indicator of perceptual capacity in very young infants. In a previous report we failed to replicate the findings on which that claim is based. Here we reanalyze some of the tapes of the first report, using a less restricted criterion for what constitutes a reach, and a much more detailed analysis of the various components of reaching behaviour. A number of components are readily distinguished and reliably observed. Infants of seven to twenty-one days show great individual variation in their reaching, from no such behaviour to a great deal. Certain clusters of the components of reaching can be used to define different reaching ‘styles’. The infants who reached most frequently in our sample all showed a dominant pattern of reaching, which in certain respects appears to be more mature than that of other babies. The finer analysis revealed no differences in the reaching behaviour to objects and pictures of objects, even among the most active reachers.