Factors Affecting Perception

Factors Affecting Perception

Our perception is not a perfect camera recording of reality — it is influenced by psychological and cultural factors. Several variables can change how we interpret the same visual information.

1. Culture

Culture affects how people perceive visual illusions, depth and spatial relationships.

Key study — Hudson (1960):

• Showed pictures with depth cues (overlap, relative size, height in the visual field) to participants from different cultures
• Western participants (experienced with 2D pictures) correctly interpreted depth in the images
• Some African participants perceived the images as flat (2D) — they did not use the depth cues
• Conclusion: interpreting depth in pictures is a learned skill, not innate — it depends on cultural experience with 2D representations

Cross-cultural illusion studies:

• Segall et al. (1963) tested the Muller-Lyer illusion across 17 cultures
• People living in carpentered environments (cities with straight lines, corners, rectangular buildings) were more susceptible to the illusion
• People living in open, circular environments (e.g. Zulu people in round huts) were less susceptible
• This supports Gregory's theory — our experience of the environment shapes the inferences our brain makes

2. Motivation

Motivation — what we want or need — can influence what we perceive.

Key study — Gilchrist and Nesberg (1952):

• Participants who had been deprived of food for several hours rated pictures of food as brighter and more vivid than non-deprived participants
• Conclusion: hunger (a motivational state) altered their perception — they were more sensitive to food-related stimuli
• This suggests perception is not purely objective — our internal states shape what we see

3. Emotion

Emotional state affects how we perceive the world around us.

• People in a positive mood tend to perceive ambiguous stimuli more positively
• People who are anxious or fearful tend to overestimate threats — they perceive neutral faces as angry, or judge heights as taller
• McGinnies (1949): participants took longer to recognise emotionally threatening words (taboo words) when flashed briefly — suggesting an unconscious perceptual defence mechanism

4. Expectation (Perceptual Set)

Perceptual set is the tendency to perceive things in a certain way based on our expectations, shaped by:

• Context — the surrounding environment primes what we expect to see
• Past experience — familiar patterns are recognised faster
• Instructions — being told what to look for changes what we notice

Key study — Bruner and Minturn (1955):

• Participants were shown an ambiguous figure that could be read as the letter "B" or the number "13"
• Those who had been shown letters beforehand perceived it as "B"
• Those who had been shown numbers perceived it as "13"
• Conclusion: prior context creates an expectation that shapes perception

5. Age

• Children and adults perceive visual information differently
• Children are more influenced by the features of a stimulus (bottom-up)
• Adults rely more on context and knowledge (top-down)
• Some illusions affect children less than adults (e.g. Muller-Lyer), supporting the idea that experience shapes susceptibility

Summary Table

Factor	How It Affects Perception	Key Evidence
Culture	Experience with the environment shapes interpretation of visual cues	Segall et al. (1963) — Muller-Lyer cross-cultural study
Motivation	Internal needs (e.g. hunger) make relevant stimuli more salient	Gilchrist and Nesberg (1952) — food images appeared brighter
Emotion	Mood and anxiety alter interpretation of ambiguous stimuli	McGinnies (1949) — perceptual defence
Expectation	Prior context and instructions create a perceptual set	Bruner and Minturn (1955) — B or 13
Age	Children and adults use different processing strategies	Developmental research on illusion susceptibility

Exam Tips

• Know at least one key study for each factor — this provides AO1 evidence
• Use the term perceptual set — it is a key concept that links many factors together
• For AO3: most studies are lab experiments (high control but low ecological validity)
• For evaluation: consider whether perception is mainly nature (biology) or nurture (experience and culture)
• A common question: "Explain how culture affects perception" — use Hudson (1960) and Segall et al. (1963)