In just 3 years, infants change from totally dependent creatures to active children who understand much about their immediate social and physical world. Developmental sciences seek to understand what infants know and feel, when and how they develop these capacities, and the processes of change. Because infants cannot tell us what they know and feel directly, researchers must devise ways to discover these answers
Methods in Infant Research:
The methods of study that researchers choose will depend, in part, on the particular question of interest. Some of the methods in Infant research are as follows:
Researchers may choose observe the everyday, spontaneous behavior of infants, interfering as little as possible with the setting and participants. Researchers measure the progress infants are making toward attaining specific milestones and then they compare an infant’s progress to the average age when developmental milestones are reached based on large representative samples of infants using standardized development tests, questionnaires, or scales developed for this purpose.
In experimental designs, researchers observe infant behaviours under controlled conditions that the researcher manipulates. Some of the experimental designs are discussed below:
Sensory Capacities Experimental Designs:
It is important to find out that if newborns have the basic sensory capacities and are developing properly, because if not, their further mental (cognitive) and emotional development may be compromised. The methods to measure sensory capacities are as follows.
One of the earliest signs that an infant can see and hear is tracking behavior. Normally, newborns will turn their eyes and heads in the direction of an interesting sound or sight, especially the human voice and face. Tracking behaviour often is examined using a standardized instrument called the Neonatal Behavioural Assessment Scale (NBAS). The NBAS has six orientation items to measure the infant’s attention and tracking of inanimate stimuli and the examiners voice and face. A failure to orient to any of these stimuli indicates that a newborn may have a serious vision or hearing problem.
Habituation relies on the observation that infants prefer to pay attentions to novel sights and sounds rather than familiar ones. A same stimulus is repeatedly presented (familiarization) to see if an infant stops paying attention to it. Then a novel stimulus is introduced. If the infant has habituated to the familiarize stimulus, the novel stimulus will re-engage the infant’s attention. In an early study, Barrera and Maurer (1981), for example, showed that 3-month-old infants can discriminate between smiling and frowning expressions by using one expression as the familiar and the other as the novel stimulus in a habituation procedure.
High Amplitude Sucking:
In High Amplitude Sucking, infants are given a non-nutritive nipple to such that is connected to a pressure transducer. A voice is turned on when the infant suck sufficiently strongly. Once the sucking pressure declines and remain below the predetermined level, it can be assumed that the infant has habituated to the redundant stimulus. When a new sound is introduced, researchers know that the infant is able to differentiate between sounds if he or she starts sucking strongly again.
Infants are presented with rectangular cards that contain black and white stripes on one side of a central peephole, while the other side is blank. Given an infant’s preference for patterned stimuli over unpatterned stimuli, if infant can detect the stimulus, he/she will fixate it. A naive observer must determine the location of the stripes based on the fixation of the child. The thinnest stripe width at which the observer can determine the location of the stripes provides a measure of visual acuity.
Conditioned Head Turning (CHD):
CHP is used to assess hearing thresholds and auditory discrimination in young infants. A sound is presented through a speaker away from infant’s gaze. If the infant turns toward the sound, an animated toy beside the speaker is activated to reward the head-turn response. The volume of the sound is varied systematically and an estimate of the hearing hold is obtained by comparing head turns toward the speaker in the presence versus the absence of the sound. The procedure can also be used to find if infants can detect a change in sounds e.g., from one rhyming sound to another.
Cognition and Learning Experimental Designs:
Cognition has to do with how the infants make sense of different sensations. Cognition is therefore, what infants learn, think, remember and know. There are many methods used to measure cognition and learning, including standardized instruments and ingenious experimental procedures.
The Bailey Scales of Infant Development (BSID) are the most widely used of contemporary tools in assessing the general cognitive level of infants. The BSID presents test items arranged in a development sequence. The child’s responses to these tasks determine his or her developmental level. The BSID has a set of items tapping mental capacity that is summarized by the Mental Development Index (MDI), and a motor skill set summarized by the psychomotor Development Index (PDI). These scores are like IQ scores, where 100 designate average performance of age, with a range of 50-150.
Rate of habituation:
The rate of habituation indicates how quickly an infant habituates. It is an indication of brain integrity and fundamental cognitive competence. For example Lewis (1969) showed that older infants needed less looking time to habituate to repeated trials of a visual display than younger infants. Rate of habituation is thought to reflect the fundamental cognitive processes of sensing, perceiving and remembering.
Young infants will really watch and track moving objects; their visual and facial expressions when an object deviates from a path are good ways to infer what infants expected to happen. Infants typically watch an event, for example, an object appearing in different locations successively. The same action is then repeated several times so that infants can learn to predict the object’s location. On the test trial, the object’s appearance in the expected location is delayed. Monitoring of eye movements allows researchers to observe whether the infants anticipated the next location, indicating that they have understood that there is a sequence and are able to predict the object’s next appearance.
Contingency or Operant Learning:
Infants use many responses to explore, or operate on the environment, including vocalizing, touching, kicking, puling, banging, etc. The relation between such behaviours (called operands) and the consequences they produce is called a contingency. Operant behavior will increase when it is followed by a rewarding consequence. Contingency methods assess whether infants behaviors increase and decrease systematically, indicating learning of the relation between the behavior and the rewarding consequence.
Imitation is another way that infants learn how to act in the world. Researchers are interested in what behaviors infants will imitate (e.g., facial actions, sounds or gestures) and who (or what) they will imitate at a given age. Imitation shows what infants regard as interesting or important behavior as well as their ability to perceive and process similarities between their own actions and those of others.
Social- emotional behavior experimental designs:
Most studies of early behavior focus on mother infant interaction. Several structured procedures have become fruitful methods for studying particular aspects of mother-infant interaction. These procedures examine how infants react when their mother’s usual pattern of responding changes.
Still- Face Procedure:
Mothers usually assume an animated style, coaxing the baby to interact by using exaggerated facial and verbal expressions. The still- face procedure was designed to see how infants react when this expectation is violated. The mother violates this expectation by assuming still face. Usually the infant attempts to get her to respond by smiling or talking, when these behaviors fail, the infant withdraws and turns away. Typically, infants quickly resume play when their mothers re engage following the still- face period.
Attachment strange situation:
Sometimes after 6 months, most infants develop a strong emotional attachment to the primary caregiver, usually their mother. One of the most influential procedures used to study the development the quality and outcomes related to this first emotional relationship is the “Strange Situation (SS)”. The SS shows that, although the infant is able to move freely about the environment, the mother serves as a secure base that the infant will seek when stressed. The procedure is comprised of eight increasingly stressful episodes in which a stranger interacts with the infant in the mother’s presence or alone. The most stressful episode is when the infant is left entirely alone. The reunion episode that follows assesses the calming effect of the mother’s return. The infant’s behavior during the separation and reunion allows researchers to classify the maternal child relationships into different attachment types.
Psychophysiological measures of Infant attention:
Psychophysiological measures are useful in the study of infant attention and infant brain development. Psychophysiology, which studies psychological processes using physiological measures, is forced on the psychological processes themselves as well as their relation to the processes affecting the physiological measures.
Heart Rate (HR):
The rate of which the heart beats (beats/min) changes as a function of simulation. Infants usually show increased HR to fearful stimuli (defensive reaction) and decreased HD to an interesting stimulus (e.g, a face, a speech sound, a taste), this is interpreted as evidence that baby finds the stimulus interesting.