How does perceptual development work?

There is a difference between perception and sensation. Sensation is the processing of basic information from the external world, through sensory receptors in the sensory organs and the brain. Perception is a process focusing on organizing and interpreting sensory information. 

How does visual development work?

In the last years,the visual capacity of babies was underestimated. Research shows that babies have a greater visual capacity than always believed.Research was done through preferential looking technique and habituation. The preferential looking technique is a method for research of the baby's visual attention, whereby babies are presented with two patterns or two objects at the same time and eventually the pattern/ object is preferred. Habituation is a method of researching the sensory and perceptual development. The baby is repeatedly presented a stimulus until it gets used to it and shows a reduced response. Then a new stimulus is presented. If the reaction of the baby suddenly increases, one can conclude that the baby is capable of differentiating between old and new stimuli.

By using the preferential viewing technique, researchers are able to assess various visual aspects of babies. Visual acuity is the degree of visual discrimination. Normally babies prefer strong visual contrasts, such as black and white. The preference arises through the low contrast sensitivity of babies. Contrast sensitivity is the ability to distinguish between light and dark areas in visual patterns. Babies have low contrast sensitivity because the cones in the eyes are not well developed yet. Cones are light-sensitive neurons, which are concentrated in the fovea of ​​the eye. The fovea is the central area of the eye. The cones of babies capture only 2% of the light entering the fovea, while adults absorb 65% of the light that enters the fovea. The brains of babies respond to a color change to another category, but not to a color change within a certain category.

Babies scan the environment for moving objects, this is called visual scanning. The objects/ people have to move slowly, otherwise babies are quickly distracted. They cannot follow rapid movements because their eye movement are quite jerky. 

Perceptual constancy is the perception of objects constant in size, shape, colors, etc., despite a change of the retinal image of the object. Babies are able to experience perceptual constancy.   

Another crucial perceptual skill is object segregation. Object segregation is the perception of boundaries between the objects. Through the movement of different objects together, babies can see if there is only object or multiple objects. As babies grow older, they use general knowledge of the world to distinguish objects.

Optical expansion occurs when an object comes closer and appears to be bigger and bigger.Babies are sensitive to this cue at an early stage. When this phenomenon is presented, the babies start to blink their eyes. Another phenomenon is binocular inequality: the difference between the retinal image of an object in one eye and the retinal image of an object in the other eye. Resulting in two different signals send to the brain. The closer we are to the objects we view, the greater the inequality in location between the two images of both eyes. The further the objects away, the more the images of both eyes match in location. This process is called stereopsis, the perception of depth. When babies are between 6 and 7 months old they become more sensitive to a variation of monocular depths cues, also called pictorial cues. These are perceptual depth cues, such as relative size, seeable with only one eye.

From birth on,the attention of babies is drawn to faces. Babies prefer the face of their mother. Then they develop a preference for faces with the same gender as their primary caretaker. In the first year of life, babies develop facial perception with the help of perceptual narrowing: learning to discriminate between the types of faces they regularly encounter in their environment. The other-race effect proofs this, it means that individuals find it easier to distinguish between faces of their own race than between faces of another race. This has nothing to do with your own gender, but with the characteristics in the immediate environment of the child. Babies also seem to prefer handsome faces.Facial perception can provide important information about autism spectrum disorders, because the individuals often show difficulty with facial perception and memory of faces.  

How does auditory development work?

A lot of babies, when hearing sounds, are turning into the direction of the sound. Locating a perceived sound is called auditory localization. Babies are mainly sensitive to music. They have a preference for consonant music instead of dissonant music. Babies also react to the rhythm of music. They try to move their feet and stamp to the rhythm of the music. Babies have a different sense of rhythm than adults. After two weeks of listening to balkan  music, babies could detect changes in complex rhythms, while adults could not. Showing that, with experience a process of perceptual narrowing starts: development changes in which experience fine - tunes the perceptual system. 

Babies recognize two-dimensional versions of three-dimensional objects. However, sometimes they pick up pictures, which could suggest that they do not understand that the pictured object is not the real object. After 19 months and enough experience with pictures, children stop examining pictures with their hands. It seems as if they understood that pictures are not to be picked up, but to look at. Children from cultures thatgrew up without pictures have more difficulty understanding the relationship between two-dimensional pictures and three-dimensional objects. Experience is crucial for this.  

When does the ability to taste and smell develop? 

Tasting and smelling develops before birth. They show a preference for sweet and natural nutrients, such as breast milk. Babies before birth, have a very strong sense of smell. Smell plays a big role in recognizing your own mother.

Why is touch important for babies?

Touch is very important for the development of a newborn baby. The first few months the development mainly happens through oral exploration. Think about the fact that babies put everything they see in their mouths. After four months, babies begin to gain more control over their hand and arm movements.

What is intermodal perception?

Intermodal perception is the combination of information gathered by two or more senses. Research has shown that babies have different forms of auditory-visual intermodal perception. The following study investigated it: two screens are presented to the baby and through the boxes a certain sound that matches the images on one of the screens is played. It is shown that the baby looks longer at the screen corresponding to the sound. A demonstration of auditory-visual mixing is the McGurk effect. A video is shown on which a person says 'go', while the word 'ba' is audibly spoken. A person who both looks and listens will say that he or she hears 'da'. This effect can already be seen in children aged 4.5 months.

How does the motor development progress?

Which reflexes does a baby have?

After birth, the baby's movements are quite uncoordinated, mostly because they experience the full effects of gravity. A baby has different reflexes. Reflexes are innate and unchangeable patterns of actions that arise in response to certain stimuli. Examples of reflexes are: grasping, sucking and swallowing. A not present reflex can indicate a brain damage. 

What are the so called motor milestones?

When the baby gets older, it learns to lift his/ her head, crawl, stand, and eventually walk. There are some cultural differences here. In some countries (eg China and Paraguay) motor movements are not encouraged  and the child is kept close to the parents for safety reasons. On the other hand, in some african cultures, motor development is strongly promoted.

The modern view of motor development?

Previous theories argued that motor development is governed by brain maturastion. However, current theories emphasize that motor development results form a confluence of many factors, such as the development of neural mechanisms, proliferation of strength, more control over posture and balance and perceptual skills.

The steppping reflex is a neonatal reflex in which a baby first lifts one leg and then the other in a coordinated pattern that looks like walking. It normally disappears after two months, which was attributed to cortical development. However, a study showed that practicing the walking reflex caused it to continue. Follow-up research shows that it is probably due to rapid weight gain in babies, where the legs become heavier but not strong enough.

How to expand the world of a baby?

Babies are initially limited to pre-reaching movements: clumsy swiping towards the general vicinity of objects they see. Finally,at around 3-4 months old, they successfully able to reach an object. However, the movements are still somewhat jerky and uncontrolled. At about 7 months, when babies gain the ability to sit, their reaching is reasonably smooth and straight to the target. By 8 months babies reach an object faster if an adult is present.

When babies are 8 months old, they are competent enough to move themselves through the environment for the first time in their lives. This is called self-locomotion. However, it also creates challenges: there are slippery floors and other obstacles. Sometimes things go wrong. Think of scale errors: the attempt of a child to try to perform an action with a miniature replica, which is impossible due to the large discrepancy in the size of the child and the object.

To test depth perception in babies, researchers designed a visual cliff. It is  a cliff with firm plexiglas over it. The mother stands on the other side of the cliff and calls the child. Babies do not cross the 'cliff', which indicates that they understand the significance of depth cues and relative size. In another study, babies were stimulated to crawl or walk on different ramps. It turned out that children can not yet properly assess what they can and can not do. It also mattered whether the parent stimulated the child. Through stimulation a child could walk down a steep hill faster. This is also called social referencing: the child uses the emotional response of another person to decide how to behave in an uncertain situation.

How do babies learn ?

There are different ways of learning babies use to gain knowledge with the help of personal experiences and the world around them: 

Habituation: recognizing a previous situation/ object leads to habituation. In other words: the reaction to an earlier experience/ object leads to a reduced reaction when this object is presented more often. When a new situation/ object is presented, the response increases and attention is paid to the relevant new stimuli.

Perceptual learning: through differentiation and affordances. Differentiation is the extraction of the relationshipa that remain constant from the ever changing environment. For example an angry face with an angry sound. Affordances hold the possibilities for actions, through certain objects and situations.

Statistical learning: simply picking up information from the environment, through associations that arise between stimuli in a statistically predictable pattern.

Classical conditioning: classical conditioning is a form of learning that consists of making associations between a neutral stimulus and a stimulus that always provoked a certain reaction. An unconditioned stimulus (UCS) in classical conditioning is a stimulus that provokes a certain reaction. An unconditioned reaction (UCR) in classical conditioning is a certain reaction triggered by the unconditioned stimulus. The conditioned stimulus (CS) in classical conditioning is a neutral stimulus that is repeatedly combined with the unconditioned stimulus, in order to ultimately trigger the unconditioned response. The  conditioned reaction (CR) in classic conditioning is a certain reaction that is combined at a given moment with the conditioned stimulus. So: first the UCS leads to a UCR, then a CS from a UCS leads to a UCR, and eventually a CS leads to a CR.

Instrumental conditioning or operant conditioning: operant conditioning is a form of learning that consists of the relationship between a person's own behavior and the consequences that arise from the behavior. By means of rewards and punishments the behavior is influenced in a positive or a negative way. Positive reinforcement is a reward that follows certain behavior and thus increases the likelihood that the behavior will be shown again in the future. Punishments reduce and eventually make certain behavior disappear. 

Observational learning / imitation: someone learns by observing/ imitating other people. Also someone's intentions for the particular behavior can be learned. Important brain systems for imitation is the mirror neuron system. This system becomes active when others are observed and shows brain reactions as if the person observing carries out the action himself.

Rational learning: the use of previous experiences to predict what will happen. One way to investigate are the violation-of-expectation paradigms. Here the astonishment of babies is looked at, when unexpected outcomes arise.

Active learning: active learning is learning through reacting to the world, instead of passively observing objects and events.   

How does the cognition develop?

Theorists of cognitive developments have different opinions on the influences ofinnate knowledge structures and special purpose learning mechanisms. Nativists believe that babies are born with existing knowledge about the physical world. Constructivists believe that babies are born with specialized mechanisms ensuring that the babies are able to obtain knowledge about the world quickly and efficiently. Empiricists believe that babies are born with generalized mechanisms that ensure the acquiring of gradual knowledge.   

What do babies know about objects?

Piaget stated that young children do not search for objects they can not see. However, it has been shown that children do it anyway, because for example, they search for objects in the dark. Other evidence comes from the violation-of-expectancy paradigm where babies are exposed to an event that evokes surprise or interest, even if it violates something the baby sees as the truth.

What do babies know about the physical world?

Research shows that babies are already aware of concepts such as gravity and relationships between objects.

What social knowledge do babies have?

Babies of a few months seem to understand that behavior has a purpose. Children eventually learn to understand the intentions of others by finding out what kind of objects can have intentions. If objects 'react' appropriately, a baby is more inclined to view the object as something with an intention. Even if it is a blob moving on the basis of instructions from a researcher.Before their first year of life, children already learned a lot about how people behave and how their behavior is related to their intentions and goals.