Tactile localization promotes infant self-recognition in the mirror-mark test.

Mirror self-recognition has been hailed by many as a milestone in the acquisition of self-awareness with respect to phylogenesis and human ontogenesis.1,2,3,4,5,6 Yet there has been considerable controversy over the extent to which species other than humans and their closest primate relatives are capable of mirror self-recognition, and to the mechanisms that give rise to this ability.1,7 One influential view is that mirror self-recognition in humans and their closest primate relatives is a cognitive advance that is a product of primate evolution, stemming from more recently evolved neural structures and networks that develop through experience-independent mechanisms during ontogenesis.1 In contrast, we show that the development of mirror self-recognition in human infants is a perception-action achievement, building on infants' ability to localize and reach to targets on the body. Infants who were given experience reaching to tactile targets on their bodies in the months prior to recognizing themselves in a mirror achieved mirror self-recognition earlier than infants in either a yoked age-matched control group or a longitudinal control group without such experience. Our results demonstrate that self-touch functions as an intermodal gateway through which infants learn how to localize and reach to stimuli on their bodies, including those that can only be seen in a mirror. These findings identify an overlooked role for the routine activity of self-touch in establishing a representation of the body and suggest that the development of human self-awareness is rooted in self-directed action.

Dynamic emotional messages differentially affect 6-month-old infants' attention to eyes and gaze cues.

Infants often experience interactions in which caregivers use dynamic messages to convey their affective and communicative intent. These dynamic emotional messages may shape the development of emotion discrimination skills and shared attention by influencing infants' attention to internal facial features and their responses to eye gaze cues. However, past research examining infants' responses to emotional faces has predominantly focused on classic, stereotyped expressions (e.g., happy, sad, angry) that may not reflect the variability that infants experience in their daily interactions. The present study therefore examined forty-two 6-month-old infants' attention to eyes vs. mouth and gaze cueing responses across multiple dynamic emotional messages that are common to infant-directed interactions. Overall, infants looked more to the eyes during messages with negative affect, but this increased attention to the eyes during these message conditions did not directly facilitate gaze cueing. Infants instead showed reliable gaze cueing only after messages with positive and neutral affect. We additionally observed gender differences in infants' attention to internal face features and subsequent gaze cueing responses. Female infants spent more time looking at the eyes during the dynamic emotional messages and showed increased initial orienting and longer looking to gaze-cued objects following positive messages, whereas male infants showed these gaze cueing effects following neutral messages. These results suggest that variability in caregivers' communication can shape infants' attention to and processing of emotion and gaze information.

The Human Face Becomes Mapped as a Sensorimotor Reaching Space During the First Year.

Although recent behavioral and neural research indicates that infants represent the body's structure, how they engage self-representations for action is little understood. This study addressed how the human face becomes a reaching space. Infants (N = 24; 2-11 months) were tested longitudinally approximately every 3 weeks on their ability to reach to a vibrating target placed at different locations on the face. Successful reaches required coordinating skin- and body-based codes for location, a problem known as tactile remapping. Findings suggest that a functional representation of the face is initially fragmented. Infants localized targets in the perioral region before other areas (ears/temples). Additionally, infants predominantly reached ipsilaterally to targets. Collectively, the findings illuminate how the face becomes an integrated sensorimotor space for self-reaching.

Development of Infant Reaching Strategies to Tactile Targets on the Face.

Infant development of reaching to tactile targets on the skin has been studied little, despite its daily use during adaptive behaviors such as removing foreign stimuli or scratching an itch. We longitudinally examined the development of infant reaching strategies (from just under 2 to 11 months) approximately every other week with a vibrotactile stimulus applied to eight different locations on the face (left/right/center temple, left/right ear, left/right mouth corners, and chin). Successful reaching for the stimulus uses tactile input and proprioception to localize the target and move the hand to it. We studied the developmental progression of reaching and grasping strategies. As infants became older the likelihood of using the hand to reach to the target - versus touching the target with another body part or surface such as the upper arm or chair - increased. For trials where infants reached to the target with the hand, infants also refined their hand postures with age. As infants became older, they made fewer contacts with a closed fist or the dorsal part of the hand and more touches/grasps with the fingers or palm. Results suggest that during the first year infants become able to act more precisely on tactile targets on the face.