Infant attention, heart rate, and looking time during habituation/dishabituation

Manipulation of phasic arousal by auditory cues is associated with subsequent changes in visual orienting to faces in infancy

This eye-tracking study investigated the effect of sound-induced arousal on social orienting under different auditory cue conditions in 5-month-old (n = 25; n = 13 males) and 10-month-old infants (n = 21; n = 14 males) participating in a spontaneous visual search task. Results showed: (1) larger pupil dilation discriminating between high and low volume (b = 0.02, p = 0.007), but not between social and non-social sounds (b = 0.004, p = 0.64); (2) faster visual orienting (b =  - 0.09, p < 0.001) and better social orienting at older age (b = 0.94, p < 0.001); (3) a fast habituation effect on social orienting after high-volume sounds (χ2(2) = 7.39, p = 0.025); (4) a quadratic association between baseline pupil size and target selection (b =  - 1.0, SE = 0.5, χ2(1) = 4.04, p = 0.045); (5) a positive linear association between pupil dilation and social orienting (b = 0.09, p = 0.039). Findings support adaptive gain theories of arousal, extending the link between phasic pupil dilation and task performance to spontaneous social orienting in infancy.

Developmental course of the repetition effect and change detection responses from infancy through childhood: a longitudinal study

Neuronal repetition effect (repetition suppression and repetition enhancement) and change detection responses are fundamental brain responses that have implications in learning and cognitive development in infants and children. Studies have shown altered neuronal repetition and change detection responses in various clinical populations. However, the developmental course of these neuronal responses from infancy through childhood is still unknown. Using an electroencephalography oddball task, we investigate the developmental peculiarities of repetition effect and change detection responses in 43 children that we followed longitudinally from 3 months to 4 years of age. Analyses were conducted on theta (3-5 Hz), alpha (5-10 Hz), and beta (10-30 Hz) time-frequency windows. Results indicated that in the theta time-frequency window, in frontocentral and frontal regions of the brain, repetition and change detection responses followed a U-shaped pattern from 3 months to 4 years of age. Moreover, the change detection response was stronger in young infants compared to older children in frontocentral regions, regardless of the time-frequency window. Our findings add to the evidence of top-down modulation of perceptual systems in infants and children.

Exploring priming effects of social and non-social attention getters on older infants' preferences for infant-directed speech

In infant research, various auditory/visual events are often used as attention getters to orient infants to a screen and alert them to upcoming information for their detection, discrimination, and/or recognition. Importantly, the influence of attention-getters on infants' performance has rarely been systematically evaluated, even though these attention cues could be affecting subsequent information processing. This study investigated whether specific attention-getters could prime infants' preferences for infant-directed speech (IDS) compared to adult-directed speech (ADS). Both a non-social and a social prime were chosen with the prediction that the social prime would strengthen infants' attention to IDS on a subsequent trial, but the non-social prime would have no differential effect on subsequent attention to either speech type. A total of 20 12- to 18-month old infants were presented with either a nonsocial (rotating form + chimes) or social (smiling female + voice) prime in an infant-controlled, speech preference procedure with both IDS and ADS speech types. Given previous research, we predicted that infants would show significantly more attention on trials during which looking produced IDS, but that this preference would be significantly augmented for infants in the condition receiving a social attention-getter before each trial. Results did not bear out this prediction, although we found a consistent, robust preference for IDS. The results will be discussed in terms of why these attention getters did not affect subsequent processing of two very different speech types, and what future modifications may be necessary in order to examine roles of attention getters in affecting experimental outcomes in infancy research. A secondary benefit of the findings is that we empirically established a growing preference for IDS in infants as old as 18-months of age.

Nemaline myopathy with KLHL40 mutation presenting as congenital totally locked-in state

We report a case of nemaline myopathy with KLHL40 mutation, presenting as congenital totally locked-in state. At birth, a male patient developed hydrops fetalis, which was diagnosed based on the generalized edema and pleural effusion and could perform no significant spontaneous movements. His eyes were open, without blinking, and the eyeballs were locked in the midposition. He could not express his intentions by vocalization or moving his trunk, extremities, facial muscles, mouth, eyelids, or eyeballs in response to ambient events or personal interactions. Electrophysiological tests and neuroimaging revealed no evidence of visual or auditory impairment that might indicate a lack of sensory perception, and no evidence of impaired consciousness or intellectual disorder(s) that might prevent him from recognizing ambient events or expressing his intentions. He subsequently died at 4 years of age. Our case highlights the fact that severe congenital neuromuscular disorders can present as congenital totally locked-in state, and that special attention should be provided to these patients.

The onset of sensitivity to horizontal disparity in infancy: a short-term longitudinal study

In this short-term longitudinal study, infants were examined for their natural preference of a square defined by crossed horizontal disparity (either 1° or 0.5°) over a square defined by a vertical disparity (either 1° or 0.5°). The square targets were embedded in a dynamic random dot stereogram. The stimuli were presented on an autostereoscopic monitor equipped with a face-tracking device. The infants were tested weekly between 6 and 16 weeks of age. Four experiments were conducted. In two experiments, the infants were examined with the forced-choice preferential looking (FPL) method for their ability to perceive either 1° or 0.5° horizontal disparity. In the remaining two experiments, the classical natural preference (CNP) method (measurement of looking times) was applied. According to the results of the FPL experiments, mean relative preference for the horizontal disparity square became significant at 8 weeks of age. The CNP data indicated an onset of stereopsis at 12-15 weeks. The mean relative preferences for horizontal disparity indicated by the CNP method were smaller than those found in the FPL experiments. Thus, the FPL method was more sensitive than the CNP method in the measurement of infant responsiveness to crossed horizontal disparity.

The comparator model of infant visual habituation and dishabituation: recent insights

Current knowledge of the perceptual and cognitive abilities in infancy is largely based on the visual habituation-dishabituation method. According to the comparator model [e.g., Sokolov (1963a) Perception and the conditioned reflex. Oxford: Pergamon Press], habituation refers to stimulus encoding and dishabituation refers to discriminatory memory performance. The review also describes the dual-process theory and the attention disengagement approach. The dual-process theory points to the impact of natural stimulus preferences on habituation-dishabituation processes. The attention disengagement approach emphasizes the contribution of the ability to shift the attention away from a stimulus. Moreover, arguments for the cognitive interpretation of visual habituation and dishabituations are discussed. These arguments are provided by physiological studies and by research on interindividual differences. Overall, the review shows that current research supports the comparator model. It emphasizes that the investigation of habituation and dishabituation expands our understanding of visual attention processes in infants.