Sensation Perception and

Attention

Mr. Narayan K Ghorpade

Asst, prof

Bharati Vidyapeeth College of Nursing Sangli

Maharashtra (India)

Overview

Sensation

Perception

Attention

Sensation, Perception, and Attention

How the cognitive system “registers” information

Sensation = physiological process that occurs

when information is encountered

Perception = psychological processes involved

in the immediate organization and interpretation

of sensations (influenced by our previous

knowledge, expectations, and biases)

Attention = processes devoted to the monitoring

of internal and external events, information,

objects, etc.

Sensations

Physiological reaction to encountering information (system is stimulated)

Processes in which physical energy from the environment is transduced into neural responses that represent basic information about the stimulation received by the sensory receptors.

Sensory systems respond consistently; our experiences (our perceptions) are different most of the time

Sensory information and “tools”

Visual system = light waves; fovea, receptive field, receptors (rods and cones), ganglion and bipolar cells

Auditory system = sound waves, frequency and intensity; pinna, tympanic membrane, bones of the middle ear, cochlea, hair cell receptors

Olfaction = odor molecules, hair cell receptors

Gustation = chemicals, papillae, taste buds

All systems have neural components that take the sensory “messages” to the brain

Sensation

The processes by which our sense organs

receive information from the environment.

Transduction

The process by which physical energy is

converted into sensory neural impulses.

Perception

The processes by which people select,

organize, and interpret sensations.

Sensation and Perception

Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing

Processes of Sensation &

Perception

Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing

Vision: A single candle flame from 30 miles

on a dark, clear night

Hearing: The tick of a watch from 20 feet in

total quiet

Smell: 1 drop of perfume in a 6-room

apartment

Taste: 1 teaspoon sugar in 2 gallons of water

Touch: The wing of a bee on your cheek,

dropped from 1 cm

Measuring Sensory Experience

Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing

Perception

Registering information/stimuli and apply prior

knowledge and experience to interpretation of that

information

Processing of this information can happen in two

ways:

Bottom-up or Data-Driven Processing = flow of

information from the stimulus to the brain (neural

activity), to interpretation or identification

Top-Down or Conceptually-Driven Processing =

processing starts with previous knowledge influencing

what we see, hear, touch, taste, smell

Perception

Gestalt principles of perceptual organization

Figure-ground

Organization depends on what we see as figure (object) and

what we perceive a ground (context).

Similarity

Objects that have similar characteristics are perceived as unit.

Proximity

Objects close together in space or time perceived as

belonging together.

Continuity

We tend to perceive figures or objects as belonging together if

they appear to form a continuous pattern.

Closure

We perceive figures with gaps in them to be complete.

Figure ground

You can see a white vase as figure against a black background, or two black faces in profile on a white background

Perception

Perception

Perceptual constancy

The tendency to perceive objects as maintaining

stable properties (e.g., size, shape, brightness, and

color) despite differences in distance, viewing angle,

and lighting

Size constancy

Perceiving objects as being about the same size when they

move farther away

Shape constancy

Perceiving objects as having a stable or unchanging shape

regardless of changes in the retinal image resulting from

differences in viewing angle

Perception

Factor influencing Perception

Sense organs

Brain

Memory images of past experience

Personal interest and mind set

Acquired interests

Needs and desires

Errors of perception

Illusion

Illusion is a misinterpretation of actual

perception

A false perception of actual stimuli involving a

misperception of size, shape, or the relationship of

one element to another

Hallucination

These are the sensory perceptions in the

absence of any corresponding external

sensory stimuli

Processing of Perception

Bottom-up processing

Information processing in which individual

components or bits of data are combined until a

complete perception is formed

Top-down processing

Application of previous experience and conceptual

knowledge to recognize the whole of a perception

and thus easily identify the simpler elements of that

whole

Influences on Perception

Attention

Meaning:

Attention is an active part of consciousness.

The activity of concentrating mind on a particular matter is

called attention.

Attention is not possible in the absence of consciousness, but

attention and consciousness are not one.

The field of consciousness is vast and attention is one of its

parts. For example, I am reading at this time. Book, note, table,

chair, etc., all this can be under my consciousness, but my

attention is on the words being read on the paper.

Definition:

Attention is the concentration of consciousness upon one object

rather than others – Dumvile.1938

Types of Attention Voluntary (Volitional)

Involuntary (Non- Volitional)

Voluntary attention

It demands the conscious effort on our part

For ex- solving assigned problems in Maths, answering a question in an

examination, etc

It further subdivided in two types

-Implicit (single act of will for attention )

Teacher assigns practice work to child

-Explicit ( Repeated acts of will )

Attention paid during examination to get best result

Involuntary Attention

This type of attention is aroused without the play of will or without making

a conscious effort on our part.

For ex- we give involuntary attention to loud sound, bright lights ect.

Factors affecting Attention Attention depends upon several factors. These factors may be of two

types:

A. External and B. Internal.

External Factors:

The external factors are concerned with the environment.

These are also called Objective Factors

-Size: Size has effect on attention. It is natural an unusual size attracts

attention of the people. Very big size or very small size too draws our

attention when compared with normal size. For example, a Lilliputian

(dwarf man) walking on the road too draws our attention.

-Intensity: Loud sounds, strong smells and deep colours are attractive in

nature. If a sound is intense then it would attract our attention. The thunder

is louder than a car sound. So, our attention is drawn on thunder.

Cont........

-Movement: Moving things draws our attention more than stationary one. A

moving car attracts faster than a stationary car.

-Contrast: Anything that is different from its surrounding is contrast. A black

dust in the milk drawn attention quickly. A swan among the crows attracts

suddenly.

- Repetition: If a thing or person or event is repeated several times, then our

attention drawn to it. When an advertisement is repeated in the walls drawn

our attention.

- - Duration: attention is drawn to a thing that lasts longer. A salesperson

draws attention by lengthening his voice.

- - Change: Change draws our attention easily. In the midst of continuous

noise a slight moment of silence draws our attention.

- - Novelty: Newness attracts quickly than traditional one. A new teacher

attracts the children very much in the school.

Internal Factors

The internal factors are concerned with the individual. So, these are also called

subjective factors.

Interest: we are interested in some things and disinterested in other things.

Interesting things draws our attention soon. An engineer and a botanist going

down the same path will attend entirely different things on the way. Engineer

attention will be on the buildings and botanist attention will be on the trees.

Desire: A person’s desire becomes a cause of paying attention to a thing. For

example, a person has to desire of buying a hammer. There are many things

available in a market, but when he goes to a shop where hammers are available.

Motives: Basic motives are important in drawing attention. Human motives like

hungry, thirst, sex, safety, etc., play a vital role in drawing attention. A thirst

person attention always on where water is available.

Aim/Goal: Every man has some immediate aim and ultimate goal in their life.

The immediate aim of a student is to pass in the examination while his ultimate

goal may be to become a doctor. The student, whose goal is not to pass the

examination, will not be concerned with textbooks or note, etc, but who has the

aim to pass in the examination, will at once attend to them.

Cont......

Habit: Habit is also a vital determinant of attention. The kind of habit we

found in our life, our attention is drawn to such things. if a person has

habit to play cricket, then his attention is always drawn to it, and he will

listen to cricket commentaries with attention.

Past Experience: It is also affect attention. If we know by our past

experience that a particular person is sincere to us, we shall pay

attention to whatever he advises us. If our experience is contrary, we

shall not attend even to his most serous advice.

Distraction: Meaning Distraction means the driving of attention or some interference in attention.

For example, when one is studying, the sound of a song or noise breaks in upon

attention.

The object which causes the distraction is called distractor.

Definition

Distraction may be defined as any stimulus whose presence interferes with the

process of attention or draws away attention from the object to which we wish to

attend – H.R.Bhatia.

A distraction may be defined as any factor which normally tends to break up

attention – Prem Prakash.

Sources of Distraction

The sources of distraction can be roughly divided into two - external and internal

sources.

External Factors: It is also called environmental factors. These are more common

and prominent.

Noise, music, improper lighting, uncomfortable seats, inadequate ventilation,

defective method of teaching, improper use of teaching aids, defective voice of the

teacher are the common external distracters in the classrooms.

Internal Factors: Emotional disturbances, ill-health, anger, fear, feeling of

insecurity, boredom, lack of motivation, feeling of fatigue, lack of interest, unrelated

subject matter are the examples for internal distracter.

Forms of Distraction:

Continuous Distraction: As the name suggests, it is the continuous distraction of

attention.

For example, the sound of radio or gramophone played continuously, the noise of

market place etc. Experiments say adjustment to continuous distraction takes place

quickly.

Discontinuous Distraction: This type of distraction is irregular, being interspersed

with intervals.

For example, the hearing of somebody’s voice every now and then. It interferes

with work because of the impossibility of adjustment. 31

Span of Attention:

Span of attention refers to the number of objects, letters and digits one can attend to

in a fraction of a second so as exclude eye movement or counting – Prem Praksh.

The extent or limit of the ability of a person to attend to a concentrate on

something. The length of time which a reader can concentrate on what he is reading

without thinking of anything else is called Span of attention.

Attention Span: It varies with age, physical, mental and emotional condition and

nature of material read.

Attention brings an object into consciousness. How many objects can be brought

into consciousness at a time, the number of them is called span of attention. On an

average span of attention of a child is limited to 4 to 5 whereas for adults it is within 6

to 7 letters or digits.

Putting it all together

Information

Perception