Sensation is the process whereby we receive raw information about the environment from the action of our sense organs. Wilhelm Wundt in 1879 set up the first psychological laboratory in Leipzig, Germany, in order to study sensations. The sensory systems provide our brains with the basic inputs from which our experiences are constructed. We respond to the world as we perceive it not as it is.

Nature of the sensory process

Sensation is the stimulation of sensory receptors to receive information about the outside world. Light, sound, taste, smell, cold, heat, touch, or pain can all produce different sensations. There are eight sense organs and eight corresponding sensations.

The stimulation of the senses is mechanical. It results from sources of energy like light sound, or the presence of chemicals as in smell and taste. Some of these senses work in combination and our response may be a result of this combination. The satisfaction that we enjoy on sipping coffee for example is a combination of the odor and taste of the coffee. Though vision is a very important sense to lives successfully, blind people adapt themselves to their lives and find satisfaction by inventing ways that make them lead successful lives. They channelize the available senses to maximum enjoyment and success in life. The same could be the case with other senses too. The adaptive nature of the sense organs makes life possible in the absence of one or two of those senses. These senses organs function continuously though we may not be aware of their functioning always.

Each sensory channel consists of a sensitive element called the receptor. A receptor is a group of cells specialized to respond to small changes in a particular kind of energy. Each of the receptors responds to a certain kind of physical energy. Sight responds to electromagnetic energy. Hearing responds to mechanical energy sound. Taste or gustatory sense to chemical substances.

Sensation involves a neurological activity. This physical energy which is a stimulus has to be changed into activity within the nervous system. Transduction occurs at the receptors converting physical energy into electrical potential. Each sense organ is connected to a particular part of the brain and that is why the sense-impression (sensation) results.

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According to Piaget, young children go through two distinct phases or sub-stages in cognitive development. During the Symbolic Function sub-stage, children master the ability to picture, remember, understand, and replicate objects in their minds that are not immediately in front of them. Children’s play will move from simple make-believe to plots involving more characters and scenarios, games with sophisticated rules, etc. According to Piagset, playing isn’t just fun; it is an important part of brain development.

These new cognitive abilities are helpful to young children’s everyday experiences. Children can talk about people who are traveling, or who live somewhere else, like Grandma. Piaget suggests that their thinking is rather rigid, limited to one aspect of a situation at a time. This style of thinking leads to characteristic errors, he says.

Conservation is a person’s ability to understand that certain physical characteristics of objects remain the same, even if their appearance has changed. To demonstrate the concept of Conservation, Piaget showed young children two identical cups filled with identical volumes of water. To these children, the taller cup looked like it had more volume even though the same amount of fluid filled both cups. Transformation is a young person’s able to understand how certain physical characteristics change while others remain the Same in a logical, cause and effect sequence. According to Piagets, Preoperational Children do not readily understand how things can change from one form to another. The concept of conservation can apply to numbers as well, such as rearranging six keys to make a different formation does not change the number of items present.

Piaget: Preoperational children have a style of thinking characterized by Egocentrism. Piaget believes that children under the age of 4 can’t organize things into hierarchical categories. Young children are unable to group items in larger sub-groups and smaller sub- Groups based on similarities and differences, he says. PreOperational children also believe that things are alive or have human characteristics because they grow or move, a type of thinking called Animism.

Research suggests that Piaget’s ideas about Preoperational children were not entirely correct. When young children are tested using ideas and objects that are familiar to their everyday lives, they are better able to demonstrate their abilities. Psychologists think that animism is a way that children express their imagination and process how objects work in a fashion that’s easy for them to understand. Most children know that inanimate objects aren’t alive, and can group their toys into hierarchies. In the preoperational stage children often display egocentric thought, particularly toward the end of this stage.

The next sub-stage in Piaget’s Preoperational cognitive development is the “Intuitive Thought” which spans ages 4-7 years. Children in this stage of development learn by asking questions such as, “Why?” and “How come?” These children typically hone in on one characteristic of someone or something and base their decisions or judgment on that one characteristic. De-centering, combined with the concept of conservation are prerequisites to more sophisticated logical thinking abilities.

Children in the Intuitive Thought sub-stage show many advances in cognitive skills. They shift from depending on magical beliefs to using rational beliefs to explain situations. Very young children may explain that a new house “grew out of the ground”.

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Some principles regarding physical growth can help understand a child’s physical development. The growth of a child’s body follows a directional pattern in three ways. Knowing this is important so expectations of a child’s physical abilities are appropriate. The patterns of development are:

Large to small muscle or gross to fine motor development

Large- to small-muscle development means large muscles develop in the neck, trunk, arms, and legs before the small muscles in the fingers, hands, wrists, and eyes develop. Children can walk before they can write or scribble.

Head to toe or top to bottom

A second pattern is children’s muscles develop from head to toe called cephalocaudal law. This is why babies can hold up their heads long before they can walk.

Inside to outside or center to outside

A third pattern is muscles develop from the center of the body first and then toward the outside of the body called proximodistal law. Muscles around the trunk of the body develop earlier and are stronger than muscles in the hands, feet, etc.

General to Specific Growth Growth

The large-muscle movement begins with waving of the arms and legs of infants and then develops into the more specific movements of an older child who can walk and draw a picture. So, muscle growth begins with more general abilities and becomes more specific and defined as children get older.

Differentiation and Integration in Growth

Differentiation is the process that a child’s muscles go through as he or she gains control over specific parts of the body and head. Once children have found (differentiated) the parts of their body, they can integrate the movements and combine specific movements to perform more complex physical activities, such as walking, building a block tower, or riding a bike.

Variations in Growth

Children vary in their physical abilities at different ages. Different parts of the body grow at different rates. The range of physical skills to be expected in gross-or fine-motor development will be very different for infants versus preschoolers.

Optimal Tendency in Growth

In children, growth generally tries to fulfill its potential. If growth is slowed for a particular reason, such as malnutrition, the body will try to catch up when it can do so. This is one reason why children may develop skills in later years even if delays occurred at an earlier point in their development.

Sequential Growth

Different areas of a child’s body will grow at different times. In other words, development is orderly and occurs in a pattern. Children must be able to stand before they can walk. This pattern is evident in several ways, such as rolling over before sitting up, sitting up before crawling and crawling before walking, etc.

Growth during Critical Periods

Growth in certain areas of a child’s physical development may be more important at particular times during childhood. For example, recent brain research indicates the first few years of life are very important in the development of the brain’s growth and for intellectual competence. Similarly, the critical time for the development of motor skills is between 18 and 60 months of age (1 to 5 years). Research suggests that children go through four physical growth cycles: two of slow growth and two of rapid growth. The first period of rapid physical growth goes from conception to the age of 6 months. The rate of growth gradually slows during the toddler and preschool periods. The second period of rapid growth is during puberty in the years of preadolescence and adolescence. Another period of leveling off occurs after puberty until adult growth is achieved.

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