SENSORY,ATTENTIAL AMD PERCEPTIONAL PROCESSES

HD) found to account for ADHD more reliably than other factors. Currently ADHD is considered to have multiple causes and effects. Disagreement remains over the most effective method of treatment of ADHD. A drug, called Ritalin, is widely used, which decreases children’s over-activity and distractibility, and at the same time increases their attention and ability to concentrate.

However, it does not “cure” the problem, and often also results in such negative side-effects as the suppression in normal growth of height and weight. On the other hand, behavioural management programmes, featuring positive reinforcement and structuring learning materials and tasks in such a way that minimises errors and maximises immediate feedback and success, have been found quite useful. Successful modification of ADHD is claimed with cognitive behavioural training programme in which rewards for desired behaviours are combined with training in the use of verbal self- instructions (stop, think, and then do). With this procedure, the ADHD children learn to shift their attention less frequently and to behave reflectively — a learning that is relatively stable over time.

P ERCEPTUAL P ROCESSES In the previous section we have examined that the stimulation of sensory organs leads us to experience something such as, a flash of light or a sound, or a smell. This elementary experience, called sensation, does not provide us with any understanding of the stimulus that stimulated the sense organ. For example, it does not inform us about the source of the light, sound or fragrance. In order to make sense out of the raw material provided by the sensory system, we process it further.

In doing so, we give meaning to stimuli by using our learning, memory, motivation, emotions, and other psychological processes. The process by which we recognise, interpret or give meaning to the information provided by sense organs is called perception. In interpreting stimuli or events, individuals often construct them in their own ways. Thus perception is not merely an interpretation of objects or events of the external or internal world as they exist, instead it is also a construction of those objects and events from one’s own point of view.

The process of meaning-making involves certain sub-processes. These are shown in Fig. . .

Processing Approaches in Perception How do we identify an object? Do we identify a dog because we have first recognised its furry coat, its four legs, its eyes, ears, and so on, or do we recognise these different parts because we have first identified a dog? The idea that recognition process begins from the parts, which serve as the basis for the recognition of the whole is known as bottom-up processing . The notion that recognition process begins from the whole, which leads to identification of its various components is known as top- down processing .

The bottom-up approach lays emphasis on the features of stimuli in perception, and considers perception as a process of mental construction. The top-down approach lays emphasis on the perceiver, and considers perception as a process of recognition or identification of stimuli. Studies show that in perception both the processes interact with each other to provide us with an understanding of the world. T HE P ERCEIVER Human beings are not just mechanical and passive recipients of stimuli from the external world.

They are creative beings, and try to understand the external world in their own ways. In this process their motivations and expectations, cultural knowledge, past experiences, and memories as well as values, beliefs, and attitudes play an important role in giving meaning to the external world. Some of these factors are described here. Motivation The needs and desires of a perceiver strongly influence her/his perception.

People want to fulfil their needs and desires through various means. One way to do this is to perceive objects in a picture as something that will satisfy their need. Experiments were conducted to examine the influence of hunger on perception. When hungry persons were Fig.

. : Sub-processes of Perception shown ambiguous pictures, they were found to perceive them as pictures of food objects more often than satiated (non-hungry) persons. Expectations or Perceptual Sets The expectations about what we might perceive in a given situation also influence our perception. This phenomenon of perceptual familiarisation or perceptual generalisation reflects a strong tendency to see what we expect to see even when the results do not accurately reflect external reality.

For example, if your milkman delivers you milk daily at about . A.M., any knocking at the door around that time is likely to be perceived as the presence of the milkman even if it is someone else. To demonstrate expectancy tell your friend to close her eyes. Write , , , on the board.

Ask her to open her eyes for seconds, look at the board, and note down what she saw. Repeat replacing only the , , with A, C, D viz. ‘A C D’. Ask her again to note down what she saw.

Most people write down B in place of .