Full Chapter Summary & Detailed Notes - Sensory, Attentional and Perceptual Processes Class 11 NCERT
Overview & Key Concepts
- Chapter Goal: Understand sensory processes, attention types/problems, form/space perception, socio-cultural role, reflect everyday. Exam Focus: Sensation, sense modalities, thresholds, attention selective/sustained/divided, perception principles, space/depth cues, constancies, illusions, influences. 2025 Updates: Emphasis on ADHD, perceptual organisation, illusions examples. Fun Fact: Eyes can't see very dim/bright; ears faint/loud. Core Idea: Sensation raw; perception meaningful. Real-World: Attention driving; illusions art. Ties: To cognition, consciousness. Expanded: Processes interrelated cognition; psychophysics thresholds. Global: Visual/auditory dominant; cultural shape perception.
- Wider Scope: External/internal stimuli; limitations organs; factors attention/perception.
- Expanded Content: Sensation basic; attention selection; perception construct. Theories filter/attenuation/multimode. Indian socio-cultural influences.
Introduction
While some receptors clearly observable (eyes/ears), others inside body, need devices. Chapter introduces receptors external/internal. Attention notice/register. Perception meaningful. Deceived figures/pictures. Expanded: Vision/hearing prized; lose traumatic? Improve performance sense? Discuss.
- Examples: Eyes vision; ears hearing; kinesthetic body position.
- Point: Sensory gather; attention select; perception understand.
- Expanded: Interrelated cognition elements.
Extended: Quality life activities - Aristotle. Processes help know world.
Knowing the World
World variety objects/people/events. Sense organs collect external/internal. Sensation/attention/perception interrelated cognition. Expanded: Eyes/ears/nose/tongue/skin external; kinesthetic/vestibular deep. Stimuli seen/heard/smelled/tasted/touched.
- Examples: Room things table/chair/books; outside trees/animals.
- Point: Knowledge basis senses; register kinds information.
- Expanded: Qualities size/shape/colour registered.
Extended: Attention draw objects/qualities; brain constructs meaning.
Nature and Varieties of Stimulus
External environment variety stimuli seen/heard/smelled/tasted/experienced touch. Sense organs/receptors gather. Seven organs: Five external (eyes/ears/nose/tongue/skin), two deep (kinesthetic/vestibular body position/movement). Ten varieties e.g., light bright/dim, sound loud/faint. Expanded: Stimuli provide kinds information; specialised organs deal.
- Examples: House seen; music heard; flower fragrance.
- Point: External/internal sources; qualities registered.
- Expanded: Skin touch/warmth/cold/pain receptors inside.
Extended: Human bestowed set seven organs.
Sense Modalities
Sensation initial experience stimulus/object registered sense organ. Detect/encode physical stimuli; immediate basic attributes hard/warm/loud/blue. Modalities specialised different stimuli/purposes. Limitations: Eyes not dim/bright; ears faint/loud. Psychophysics studies relationship. Absolute threshold (AL) minimum value activate; difference limen (DL) smallest difference notice. Expanded: AL not fixed; varies individuals/situations. 50% trials.
- Examples: Sugar granules water sweet AL; more sweeter DL.
- Point: Sensory system limited range; optimal intensity.
- Expanded: Defect/damage receptor/pathway/brain loss sensation.
Extended: Sense organs external/internal worlds.
Attentional Processes
Stimuli impinge simultaneously; select few. Attention selection/alertness/concentration/search. Effort allocation. Focus central; fringe vague. Divided possible practiced automatic. Selective selection limited stimuli; factors external (size/intensity/motion/novel/complex) internal (motivational biological/social needs; cognitive interest/attitude/set). Theories: Filter Broadbent bottleneck one pass; attenuation Triesman weakens others escape; multimode Johnston/Heinz three stages effort. Sustained maintain longer vigilance; factors modality/clarity/temporal/spatial uncertainty. Expanded: Span 7±2 magic number; ADHD impulsivity/hyperactivity/inattention boys; causes social-psychological; treatment Ritalin/behavioural/cognitive.
- Examples: Classroom select teacher lecture ignore noises; radar signals unpredictable.
- Point: Properties alertness/concentration/search; divided practiced.
- Expanded: Automatic no intention/unconscious/little thought.
Extended: Implications number plates; school performance ADHD.
Perceptual Processes
Sensation elementary; perception further process meaningful. Bottom-up stimulus-driven; top-down concept-driven. Perceiver attitudes/motivations/expectations/culture. Principles organisation figure-ground/grouping (proximity/similarity/continuity/closure/smallness/common region). Space/depth/distance monocular (relative size/height/linear perspective/aerial/texture gradient/motion parallax/superposition); binocular (convergence/retinal disparity). Constancies size/shape/brightness despite changes. Illusions misperception; geometrical/illusory contours. Socio-cultural influences context/expectancy/experience. Expanded: Approaches processing; perceiver active role.
- Examples: Müller-Lyer illusion; size constancy moon horizon; cultural carpentered world.
- Point: Perception construct meaning; principles organise.
- Expanded: Cues depth; illusions deceive.
Extended: Everyday reflect; socio-cultural shape.
Summary
- Humans endowed sense organs register world. Sensation provides raw inputs processed further perception.
- Sense modalities visual/auditory/taste/smell/touch/pain/warmth/cold/kinesthetic/vestibular.
- Attentional processes select stimuli; types selective/sustained/divided. Factors external/internal; theories filter/attenuation/multimode.
- Perceptual processes bottom-up/top-down; organisation principles; space monocular/binocular cues; constancies; illusions; socio-cultural influences.
Why This Guide Stands Out
Complete: All subtopics, examples, Q&A, quiz. Psychology-focused. Free 2025.
Key Themes & Tips
- Aspects: Sensation raw, attention select, perception meaningful.
- Thinkers: Broadbent, Triesman, Johnston/Heinz, Gestalt psychologists.
- Tip: Distinguish thresholds; attention theories; perception principles/cues; illusions examples.
Exam Case Studies
ADHD, illusions, depth cues, attention division.
Project & Group Ideas
- Activity 4.1: Senses lose/improve discuss.
- Activity 4.2: Divided attention day-to-day observe.
- Project: Illusions create/explain; attention factors experiment.
60+ Questions & Answers - NCERT Based (Class 11)
Part A (1 mark short), B (4 marks medium), C (8 marks long). Based on NCERT, exercises. Answer lengths: 1 mark ~2 lines, 4 marks ~5 lines, 8 marks ~10 lines.
Part A: 1 Mark Questions
1. Define sensation.
1 Mark Answer: Sensation is initial experience stimulus registered sense organ. Basic attributes like hard/warm.
2. What are sense modalities?
1 Mark Answer: Sense modalities are specialised organs dealing different stimuli. E.g., eyes vision, ears hearing.
3. Define absolute threshold (AL).
1 Mark Answer: AL is minimum stimulus value activate sensory system. 50% trials notice.
4. What is difference limen (DL)?
1 Mark Answer: DL is smallest difference two stimuli notice different. 50% trials.
5. Define attention.
1 Mark Answer: Attention is process select stimuli group others. Includes alertness/concentration/search.
6. What is selective attention?
1 Mark Answer: Selective attention is selection limited stimuli many. Limited capacity.
7. Name an external factor affecting selective attention.
1 Mark Answer: Size/intensity/motion/novelty/complexity stimuli. E.g., large/bright.
8. Name an internal factor affecting selective attention.
1 Mark Answer: Motivational biological/social needs; cognitive interest/attitude/set.
9. What is filter theory?
1 Mark Answer: Broadbent's filter theory: Bottleneck; one stimulus pass higher processing.
10. What is attenuation theory?
1 Mark Answer: Triesman's attenuation theory: Weakens others; some escape if relevant.
11. What is multimode theory?
1 Mark Answer: Johnston/Heinz multimode: Selection three stages; more effort later.
12. Define sustained attention.
1 Mark Answer: Sustained attention maintain focus longer durations. Vigilance.
13. What is span of attention?
1 Mark Answer: Span attention objects brief exposure. 7±2 magic number.
14. What is ADHD?
1 Mark Answer: ADHD is behavioural disorder impulsivity/hyperactivity/inattention. Primary school children.
15. Define perception.
1 Mark Answer: Perception process make sense raw sensory information. Meaningful understanding.
16. What is bottom-up processing?
1 Mark Answer: Bottom-up stimulus-driven; features build whole.
17. What is top-down processing?
1 Mark Answer: Top-down concept-driven; knowledge/expectations guide.
18. Name a principle of perceptual organisation.
1 Mark Answer: Proximity: Close group together.
19. What is monocular cue?
1 Mark Answer: Monocular cue one eye depth e.g., relative size.
20. What is binocular cue?
1 Mark Answer: Binocular cue two eyes e.g., retinal disparity.
21. Define perceptual constancy.
1 Mark Answer: Perceptual constancy stable perception despite changes stimulus.
22. What is illusion?
1 Mark Answer: Illusion misperception physical reality. E.g., Müller-Lyer.
23. Name a socio-cultural influence on perception.
1 Mark Answer: Context/expectancy/experience/culture. E.g., Carpentered world.
24. What is psychophysics?
1 Mark Answer: Psychophysics studies stimuli sensations relationship. Thresholds.
25. What is kinesthetic system?
1 Mark Answer: Kinesthetic system body position/movement parts.
Part B: 4 Marks Questions
1. Explain sense modalities with examples.
4 Marks Answer: Sense modalities specialised organs different stimuli. External: Eyes vision (bright/dim), ears hearing (loud/faint), nose smell, tongue taste, skin touch/warmth/cold/pain. Deep: Kinesthetic body position, vestibular movement. Examples: See house; hear music.
2. Describe functional limitations of sense organs.
4 Marks Answer: Sense organs limited range stimulation. Eyes not very dim/bright; ears faint/loud. Optimal intensity notice. Psychophysics studies. Defect/damage receptor/pathway/brain loss sensation.
3. Explain absolute threshold with example.
4 Marks Answer: AL minimum stimulus activate sensory. Varies individuals/situations; 50% trials. Example: Sugar granules water sweet; number AL sweetness.
4. Describe difference threshold with example.
4 Marks Answer: DL smallest difference notice different. 50% trials. Example: More granules previous sweetness different; number DL.
5. What is attention? Explain properties.
4 Marks Answer: Attention select stimuli many. Properties: Alertness readiness, concentration focus exclude, search look subset, effort allocation.
6. Explain selective attention factors.
4 Marks Answer: External: Size/intensity/motion/novel/complex. Internal: Motivational needs hunger; cognitive interest/attitude/set. Examples: Hungry smell food; interesting objects quick.
7. Describe filter theory of selective attention.
4 Marks Answer: Broadbent filter: Stimuli bottleneck short-term memory; selective filter one pass higher; others screened.
8. Explain attenuation theory.
4 Marks Answer: Triesman: Not blocked completely; filter attenuates strength; relevant escape e.g., name low sound.
9. Describe multimode theory.
4 Marks Answer: Johnston/Heinz: Flexible selection three stages sensory/semantic/conscious; more effort later selection.
10. Explain sustained attention factors.
4 Marks Answer: Modality auditory better visual; clarity intense/long; temporal uncertainty regular better irregular; spatial fixed better random.
11. What is span of attention? Explain.
4 Marks Answer: Span objects brief exposure. Miller 7±2 magic. Tachistoscope determine. Implications number plates easy notice.
12. Describe ADHD characteristics.
4 Marks Answer: ADHD impulsivity/excessive motor/inattention. Boys prevalent; persist adolescence. Distractible; poor school; no intelligence deficit.
13. Explain causes and treatment of ADHD.
4 Marks Answer: Causes social-psychological home/family; no biological/dietary strong. Treatment Ritalin reduce overactivity; behavioural positive reinforcement; cognitive verbal self-instructions stable.
14. Differentiate sensation and perception.
4 Marks Answer: Sensation initial basic experience attributes; perception process meaningful understanding source. Sensation raw; perception construct.
15. Explain bottom-up processing.
4 Marks Answer: Bottom-up stimulus-driven; features/parts build whole. Data analysis upward.
16. Describe top-down processing.
4 Marks Answer: Top-down concept-driven; knowledge/expectations/motivations guide interpretation downward.
17. Explain figure-ground principle.
4 Marks Answer: Figure-ground: Organise visual field figure distinct/background. Contour separate.
18. Describe proximity/similarity grouping.
4 Marks Answer: Proximity: Close/together group unit. Similarity: Similar features group.
19. Explain continuity/closure.
4 Marks Answer: Continuity: Smooth continuous pattern group. Closure: Closed/complete figures.
20. What is relative size cue?
4 Marks Answer: Relative size: Larger closer; smaller farther. Monocular pictorial.
21. Explain linear perspective.
4 Marks Answer: Linear perspective: Parallel lines converge distance. E.g., railway tracks.
22. Describe retinal disparity.
4 Marks Answer: Retinal disparity: Images two eyes differ; brain depth. Binocular.
23. Explain size constancy.
4 Marks Answer: Size constancy: Same size despite retinal change distance. Experience.
24. What is Müller-Lyer illusion?
4 Marks Answer: Müller-Lyer: Lines same length appear different arrows. Geometrical.
25. Explain socio-cultural influence with example.
4 Marks Answer: Culture shape perception e.g., carpentered world susceptible Müller-Lyer. Context/expectancy/experience.
Part C: 8 Marks Questions
1. Explain sensory processes and sense modalities.
8 Marks Answer: Sensory processes detect/encode stimuli sensation initial experience attributes. Modalities specialised: External eyes vision, ears hearing, nose smell, tongue taste, skin touch/warm/cold/pain; deep kinesthetic position, vestibular movement. Limitations range; psychophysics AL minimum notice 50% trials e.g., sugar sweet; DL difference notice e.g., sweeter. Defect loss sensation. Examples: See bright/dim; hear loud/faint.
2. Describe attentional processes types and factors.
8 Marks Answer: Attention select stimuli; properties alertness/concentration/search/effort. Types: Selective limited many factors external size/intensity internal needs/interest; divided more practiced automatic e.g., drive/talk; sustained longer vigilance factors modality/clarity/uncertainty e.g., radar. Span 7±2. ADHD impulsivity/hyperactivity/inattention boys; social causes; Ritalin/behavioural treatment.
3. Explain theories of selective attention.
8 Marks Answer: Filter Broadbent bottleneck one pass higher others screened early. Attenuation Triesman weakens; relevant escape e.g., name. Multimode Johnston/Heinz three stages sensory/semantic/conscious more effort late. Examples: Dichotic listening; cocktail party. Flexible system.
4. Describe perceptual processes and approaches.
8 Marks Answer: Perception make sense sensation meaningful. Approaches bottom-up stimulus features build; top-down knowledge guide. Perceiver attitudes/motivations/expectations/culture active. Examples: Ambiguous figures; context influence.
5. Explain principles of perceptual organisation.
8 Marks Answer: Gestalt principles: Figure-ground distinct/background; grouping proximity close, similarity similar, continuity smooth, closure complete, smallness small figure, common region enclosed. Organise features forms. Examples: Dots group lines; incomplete circle closed.
6. Describe perception of space, depth, distance.
8 Marks Answer: Monocular one eye: Relative size larger closer, height plane higher farther, linear perspective converge, aerial atmosphere, texture gradient coarse close, motion parallax near fast, superposition block far. Binocular two: Convergence eyes inward, retinal disparity images differ. Examples: Road lines; stereo vision.
7. Explain perceptual constancies.
8 Marks Answer: Constancies stable despite changes: Size same distance retinal vary; shape angle; brightness light. Experience/learning. Examples: Door shape change open; moon size horizon/sky.
8. Describe illusions with examples.
8 Marks Answer: Illusions misperception: Geometrical Müller-Lyer lines arrows, Ponzo rails; apparent movement phi flashing lights; size-weight heavy small. Deceive senses. Examples: Movie motion still images; cultural differences susceptibility.
9. Explain socio-cultural influences on perception.
8 Marks Answer: Socio-cultural context/expectancy/experience/frequency/motives/needs shape. Cultural carpentered susceptible geometrical; tribal less. Examples: Hudson pictures depth Africans difficulty; context ambiguous figures.
10. Discuss role sensory, attentional, perceptual in everyday life.
8 Marks Answer: Everyday: Sensory gather info; attentional select relevant e.g., drive focus road; perceptual understand meaningful e.g., recognise friend. Reflect illusions deceive; attention divide multitask; perception cultural differ interpretations. Improve awareness processes.
11. Explain ADHD in detail.
8 Marks Answer: ADHD common children primary; impulsivity/motor/inattention boys. Distractible; not follow; poor peer/parent; school difficulty no intelligence deficit. Causes social home/family; dietary colouring. Treatment Ritalin reduce over/distract but side growth; behavioural positive/minimise errors/feedback; cognitive rewards/self-instructions stable.
12. Compare attention theories.
8 Marks Answer: Filter early one pass; attenuation weakens escape relevant; multimode flexible three effort increases late. Filter bottleneck; attenuation threshold; multimode sensory/semantic. Examples: Name notice low; late semantic.
13. Explain grouping principles with examples.
8 Marks Answer: Proximity close group e.g., dots columns; similarity similar e.g., circles/squares; continuity align smooth e.g., curve; closure fill gaps e.g., broken circle; smallness small figure; common region enclosed group.
14. Describe monocular cues.
8 Marks Answer: Monocular: Relative size large close; height plane high far; linear parallel converge; aerial hazy far; texture dense far; motion near fast; superposition block far. Pictorial artists use.
15. Explain binocular cues.
8 Marks Answer: Binocular: Convergence eyes turn in close; retinal disparity images differ fuse depth. Physiological; stereopsis 3D.
16. Discuss perceptual constancies types/examples.
8 Marks Answer: Size constant distance; shape angle; brightness illumination. Examples: Person far small retinal but same; table top shape change view; paper white shade/sun.
17. Explain types illusions examples.
8 Marks Answer: Geometrical Müller-Lyer/Ponzo; apparent movement phi/stroboscopic movie; size-weight small heavy feel heavier; illusory contours Kanizsa triangle.
18. Discuss socio-cultural perception influences.
8 Marks Answer: Context whole/part; expectancy set; frequency familiar quick; motives/needs hungry food. Cultural carpentered angular illusions; tribal round less. Examples: Ambiguous rat/man; Hudson depth cues.
19. Explain knowing world processes.
8 Marks Answer: Senses collect external/internal; attention select/register; perception construct meaning. Interrelated cognition. Examples: Room objects select few; brain meaning.
20. Describe varieties stimulus sense organs.
8 Marks Answer: Stimuli seen/heard/smelled/tasted/touched; qualities bright/dim/loud/faint. Organs eyes/ears/nose/tongue/skin external; kinesthetic/vestibular deep. Seven organs ten varieties.
21. Explain divided attention when possible.
8 Marks Answer: Divided more one time; possible highly practiced automatic no intention/unconscious/little thought. Examples: Drive/talk/phone; effort more driving. Shoelaces tie/read words automatic.
22. Discuss attention practical implications.
8 Marks Answer: Implications: Number plates design span; school performance ADHD; traffic rules notice. Vigilance air controllers; errors fatal.
23. Explain perceiver role perception.
8 Marks Answer: Perceiver attitudes/motivations/expectations/culture active construct. Top-down knowledge guide. Examples: Hungry food salient; cultural illusions differ.
24. Describe space perception cues.
8 Marks Answer: Monocular pictorial relative size/height/linear/aerial/texture/motion/superposition; binocular physiological convergence/disparity. Examples: Paintings depth; 3D movies.
25. Discuss illusions socio-cultural aspects.
8 Marks Answer: Illusions misperception; geometrical/apparent/size-weight. Socio-cultural carpentered more susceptible angular; experience reduce. Examples: Müller-Lyer urban/rural differ.
Tip: Relate thresholds examples; theories compare; principles draw; cues classify; illusions explain.
