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I. Sensations and Perceptions

Sensations can be defined as the passive process of bringing information from the outside

world into the body and to the brain.The process is passive in the sense that we do not have tobe consciously engaging in a "sensing" process.

Perception can be defined as the active process of selecting, organizing, and interpreting the

information brought to the brain by the senses.

A) HOW TH! WO# TO$TH%

&) Sensation occurs%

a) sensory organs absorb energy fro' a physical sti'ulus in the environ'ent.

b) sensory receptors convert this energy into neural i'pulses and send the' to the brain.

() Perception follows%

a) the brain organies the infor'ation and translates it into so'ething 'eaningful.

*) *ut what does "'eaningful" 'ean+ How do we ,now what infor'ation is i'portant andshould be focused on+

&) Selective Attention - process of discri'inating between what is i'portant is irrelevant

/See's redundant selective-attention+)0 and is influenced by 'otivation.

1or e2a'ple - students in class should focus on what the teachers are saying and the overheads

being presented. Students wal,ing by the classroo' 'ay focus on people in the roo'0 who is theteacher0 etc.0 and not the sa'e thing the students in the class.

() Perceptual 2pectancy - how we perceive the world is a function of our past e2periences0

culture0 and biological 'a,eup.1or e2a'ple0 as an A'erican0 when 3 loo, at a highway0 3 e2pectto see cars0 truc,s0 etc0 4OT airplanes. *ut so'eone fro' a different country with different

e2periences and history 'ay not have any idea what to e2pect and thus be surprised when they

see cars go driving by.

Another e2a'ple - you 'ay loo, at a painting and not really understand the 'essage the artist istrying to convey. *ut0 if so'eone tells you about it0 you 'ight begin to see things in the painting

that you were unable to see before.

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SENSATION

Sensation refers to awareness of sti'ulus. Sti'ulus refers to any thing that elicits response. This

'ay be internal/changes in organ syste') or e2ternal changes /changes in surroundings). There

are five sensory organs e2cited by different types of sti'uli.

&. 5isual organ /ye)% 6ight

(. Auditory organ /ar)% Sound7. $ustatory organ /Tongue)%8he'ical

9. Olfactory organ /4ose)% 8he'ical

:. 8utaneous organ /S,in)% Te'perature0pressure

Attention

When individual focuses awareness to so'ething0 attention ta,es place. Attention is focus of

awareness. 3t has few functions li,e%

&. alerting% 3t is physical and 'ental preparedness to focus on specific sti'ulus.

(. selective function% Selectivity refers to a process by which attention is focused on sti'ulus orsti'uli of ongoing interest and other sti'uli are ignored.

7. li'ited capacity channel%li'ited capacity to carry out the tas,. We can process one tas, at a

ti'e. This causes serial processing.

9. vigilance% 'aintaining attention on a tas, continuously0 for so'e

ti'e0 is called vigilance or sustained attention. 3t has been found that attending to a tas, for long

is ta2ing0 particularly if the tas, is 'onotonous and it leads to decrease in perfor'ance.

PERCEPTION

Perception occurs when sensation carries certain 'eaning. This can be e2plained in this for'ula%

Perception ; sensation