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Sensory, Attentional and Perceptual Processes – Class 11 Psychology notes, important questions and MCQs

NCERT Class 11 Psychology, chapter 5. Notes, key terms, important questions with answers and MCQs.

Chapter overview

We know the world through sensation, attention and perception. Sensory receptors detect stimuli and convert them into neural signals; attention selects some stimuli for further processing; and perception organises and interprets sensory information to give it meaning. Perception is influenced by learning, motivation, expectations and culture, and can sometimes be mistaken, as in illusions.

Sensation and attention

Sense organs include the eye, ear, nose, tongue and skin, as well as kinesthetic and vestibular senses; each sense has an absolute threshold (minimum stimulus detected) and a difference threshold (smallest detectable change).
The eye has a retina with rods (dim light, black and white) and cones (bright light, colour); the ear converts sound waves into nerve impulses in the cochlea.
Attention is selective (choosing some stimuli), sustained (concentrating over time, vigilance) and divided (doing more than one task); factors include the size, intensity, movement and novelty of stimuli and the person's motives and interests.

Perception

Gestalt principles of perceptual organisation include figure and ground, proximity, similarity, continuity, closure and smallness.
Perceptual constancies keep size, shape and brightness stable despite changes in the image on the retina; depth perception uses monocular cues (relative size, linear perspective, overlap, texture gradient) and binocular cues (retinal disparity, convergence).
Illusions are misperceptions, such as the Müller-Lyer illusion; the phi phenomenon is apparent movement from rapidly flashing lights. Perception is shaped by learning and culture.

Key terms

Sensation: detection of stimuli by sense organs
Perception: organising and interpreting sensory information
Absolute threshold: minimum intensity of a stimulus that can be detected
Selective attention: focusing on some stimuli while ignoring others
Illusion: a misperception of a real stimulus

Important questions with answers

Distinguish between sensation and perception.2 marks

Sensation is the process of detecting stimuli through sense organs and converting them into neural signals. Perception is the process of organising and interpreting these sensations to give them meaning, using past experience and expectations.

Explain three Gestalt principles of perceptual organisation.3 marks

Proximity: objects close together are seen as a group. Similarity: objects that are similar in shape or colour are grouped together. Closure: we tend to fill gaps and see incomplete figures as complete. Others include continuity and figure-ground.

Describe the types of attention and the factors that influence it.5 marks

Attention is the process of selecting certain stimuli from the many that reach our senses for further processing. It has several types. Selective attention involves focusing on a limited number of stimuli while ignoring others, as when we listen to one person in a noisy room (the 'cocktail party' effect). Sustained attention, or vigilance, refers to the ability to maintain concentration on a task over a long period, as for radar operators or air traffic controllers; it can decline with fatigue and monotony. Divided attention refers to performing more than one task at a time, which becomes easier when tasks are well practised and automatic. Span of attention refers to the number of objects that can be attended to at one time. Several factors influence attention. External factors relate to the stimulus: its size, intensity, movement, novelty, contrast, repetition and complexity; for example, a large flashing advertisement attracts attention. Internal factors relate to the person: motives and needs, such as a hungry person noticing food; interests, attitudes and expectations; and cognitive styles. Attention problems include attention-deficit hyperactivity disorder (ADHD), in which children have difficulty sustaining attention and controlling impulses. Understanding attention helps in education, advertising, safety and workplace design.

Quick revision

Sense organs and thresholds.
Types and determinants of attention.
Gestalt principles; constancies; depth cues.
Illusions and socio-cultural influences.

Exam tips

Remember rods for dim light and cones for colour.
Learn the Gestalt principles with one example each.

Practice MCQs

Detection of stimuli by sense organs is called
1. sensation
2. perception
3. attention
4. memory
Show answer
Answer: (a) sensation. It comes before perception.
Cells in the retina responsible for colour vision are
1. rods
2. cones
3. neurons of the ear
4. taste buds
Show answer
Answer: (b) cones. They work in bright light.
A misperception of a real stimulus is called
1. hallucination
2. delusion
3. sensation
4. illusion
Show answer
Answer: (d) illusion. The Müller-Lyer is an example.
Focusing on some stimuli while ignoring others is
1. divided attention
2. sustained attention
3. selective attention
4. perception
Show answer
Answer: (c) selective attention. It filters information.
The minimum intensity of a stimulus that can be detected is the
1. difference threshold
2. absolute threshold
3. adaptation
4. constancy
Show answer
Answer: (b) absolute threshold. It differs between people.
The Gestalt principle by which we group nearby objects together is
1. similarity
2. closure
3. proximity
4. continuity
Show answer
Answer: (c) proximity. Things close together seem to belong.
A plate seen at an angle still appears round because of
1. depth perception
2. sensory adaptation
3. illusion
4. shape constancy
Show answer
Answer: (d) shape constancy. The brain corrects the retinal image.
Retinal disparity, a cue for depth perception, works because
1. one eye is closed
2. the image is upside down
3. objects become blurred
4. each eye receives a slightly different image
Show answer
Answer: (d) each eye receives a slightly different image. It is a binocular cue.

All chapters of Class 11 Psychology

Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.