(c) Transduction

Transduction is the process by which sensory receptors convert physical stimuli (light, sound, pressure) into neural signals that the brain can interpret.

(b) Perception can be influenced by contextual cues

In the Müller-Lyer illusion, two lines of equal length appear different because of the direction of arrowheads, showing that our interpretation of stimuli is influenced by surrounding context.

(b) Selective attention

The cocktail party effect demonstrates our ability to focus on one conversation in a noisy environment while filtering out others — a clear example of selective attention.

(c) Closure

The principle of closure states that we tend to perceive incomplete figures as complete by mentally filling in the missing parts.

(b) Binocular cue

Retinal (binocular) disparity relies on the slight difference between the images received by each eye. The brain uses this difference to perceive depth. It requires both eyes.

Sensation is the raw input; perception is the meaningful interpretation of that input.

1. Relative size: When two objects are of similar actual size, the one that produces a smaller retinal image is perceived as farther away. E.g., a car far away appears smaller than one nearby.

2. Interposition (overlap): When one object partially blocks another, the blocking object is perceived as closer. E.g., a book placed on top of a stack appears closest.

3. Linear perspective: Parallel lines (like railway tracks) appear to converge as they extend into the distance. The point of convergence suggests greater distance.

Perceptual constancy is the tendency to perceive familiar objects as having a stable size, shape, colour, and brightness despite changes in the sensory input reaching our eyes.

Types:

1. Size constancy: We perceive an object as the same size regardless of its distance from us. E.g., a friend walking away does not appear to shrink, even though the retinal image of the friend becomes smaller.

2. Shape constancy: We perceive an object as the same shape regardless of the viewing angle. E.g., a circular plate viewed from an angle projects an elliptical image on the retina, but we still perceive it as circular.

Gestalt psychologists proposed that the brain organises sensory information according to certain innate principles — often summarised as “The whole is greater than the sum of its parts.”

1. Figure–Ground:

• We tend to perceive objects (figure) against a background (ground)
• Example: Words (figure) on a page (ground); Rubin’s vase — the image can be seen as either a vase or two faces

2. Proximity:

• Elements that are close together are perceived as belonging to the same group
• Example: ●● ●● ●● — we see three pairs of dots, not six individual dots

3. Similarity:

• Elements that are similar (in colour, shape, or size) are grouped together
• Example: A row of alternating red and blue circles — we see groups of same-coloured circles

4. Continuity:

• We tend to perceive elements arranged in a smooth line or curve as belonging together
• Example: Two crossing curves are seen as two continuous lines rather than four separate segments

5. Closure:

• We tend to fill in gaps to perceive incomplete figures as complete
• Example: A circle with a small gap is still perceived as a complete circle

6. Symmetry:

• Symmetrical elements are perceived as a unified whole
• Example: Symmetrical bracket shapes [ ] are perceived as a single object

Significance: These principles show that perception is an active, organised process — not merely a passive recording of stimuli. They have applications in design, advertising, and art.

Attention is the cognitive process of selectively concentrating on one aspect of the environment while ignoring others. It is essential because our sensory systems receive far more information than we can process at any given moment.

Types of Attention:

• Selective attention: Focusing on one stimulus while ignoring others
• Sustained attention (vigilance): Maintaining focus over a prolonged period
• Divided attention: Attending to multiple stimuli or tasks simultaneously

Factors Influencing Selective Attention:

A. External (stimulus) factors:

1. Size: Larger stimuli are more likely to attract attention (e.g., a large advertisement)
2. Intensity: Brighter lights, louder sounds attract more attention
3. Novelty: Unusual or unexpected stimuli capture attention (e.g., a person in costume on the street)
4. Movement: Moving objects attract attention more than stationary ones
5. Contrast: A stimulus that stands out from its background draws attention (e.g., a red dot on a white page)
6. Repetition: Repeated stimuli (like a recurring alarm) capture attention

B. Internal (perceiver) factors:

1. Motivation: We attend to stimuli relevant to our current needs (e.g., a hungry person notices food advertisements)
2. Interest: We attend more to things we find interesting
3. Expectations (perceptual set): We attend to stimuli we expect to encounter
4. Past experience: Familiar stimuli are processed more quickly
5. Emotional state: Anxious individuals may attend more to threatening stimuli

Significance: Understanding attention is important in education (maintaining student focus), driving safety, workplace efficiency, and clinical psychology (attention deficit disorders).

(a) Both A and R are true and R is the correct explanation of A

Colour constancy is the tendency to perceive the colour of a familiar object as relatively constant despite changes in illumination. The white shirt continues to appear white because our perceptual system compensates for the change in lighting conditions.

(i) Neha is demonstrating two types of attention:

• Selective attention — she focuses on her textbook while filtering out the TV, conversation, and barking
• Sustained attention — she maintains this focus for 45 minutes

(ii) The cocktail party effect is demonstrated when Neha immediately notices her name being called, despite filtering out other sounds. This shows that even when we are selectively attending to one source, personally relevant stimuli (like our own name) can break through the attentional filter and capture our awareness.

(iii) The decline in Neha’s ability to maintain focus after a prolonged period is called vigilance decrement — a natural decrease in sustained attention that typically occurs during monotonous or demanding tasks.

(iv) Two strategies:

1. Take short breaks (e.g., 5–10 minutes every 30–40 minutes) to allow attentional resources to recover — the Pomodoro technique
2. Reduce distractions — study in a quieter room, use noise-cancelling headphones, or request family members to lower the TV volume during study hours

(i) Meera and Karan perceive the same cloud differently because perception is not merely a passive recording of sensory data — it is an active, constructive process influenced by the perceiver’s knowledge, expectations, experiences, and interests. The same physical stimulus (cloud) is interpreted differently because each person brings their own mental framework to the interpretation.

(ii) This situation is best explained by top-down processing — perception guided by existing knowledge, expectations, and mental schemas rather than by the raw sensory data alone. The ambiguous shape of the cloud allows each person’s prior experiences and imagination to shape what they “see.”

(iii) Two internal factors:

1. Past experience: Meera may have recently seen pictures of rabbits or is fond of animals, making her more likely to interpret the shape as a rabbit. Karan may have recently watched a movie about ships.
2. Interests and motivation: Individual interests influence what patterns the brain seeks out in ambiguous stimuli. A person interested in maritime adventures might see a ship; an animal lover might see a rabbit.