Week 1 - Visual Illusions Flashcards
What is the definition of an Illusion
- An instance of a wrong or misinterpreted perception of a sensory experience
- A deceptive appearance or impression
seeing the world around you is neither
straightforward nor reliable, and very much involves psychological
processes
1. Detecting change
What does detecting change show
Limits of attention
- In focus
- In capacity
- seeing is active
What is Change Blindness
- Also ‘‘Inattentional Blindness’’
- You dont know where to direct your attnetion, so you can miss large changes
- The Flash stimmulates a saccade: Rapid change of fixation
- Has to move around rapidly to piece together the scene
What is the Human Fovea
Involved in Inattentional Blindess
- Cones only
- Processing foveal output account for 50% of the visual corex
1.5mm wide
2. Ambiguous Figures
What are ambiguous figures
- Images that have two valid interpretations (e.g. The Necker Cube)
- Necker cube: discovered by Louis Albert Necker
Melcher and Wade (2006) claim to have found ambiguous elements in prehistoric cave art
What is the Dominant theory for Amiguous Figures?
‘Neural Satiation’
- Neurons supporting one interpretation become fatigue
- Eventually neurons supporting the other interpretation take over
- Until they become fatigued, then repeat, increasingly quickly
This is a ‘Bottom-Up’ approach
HOWEVER, most participants do not experience reversal unless…
- Informed of the ambiguity
- Told what the two interpretations are
- Intend to change their interpretation
Suggesting ‘top-down’ influences too.
What do Amiguous figure show
- Perception is not passive
- Involves the interplay between low-level processes, and higher-level cognitive processes
Richard Gregory described percepts as HYPOTHESIS…
- Perceptual input is always more or less ambiguous
- Ambiguous stimuli are constructed to maximise the ambiguity between two alternatives
3. Visual Illusions
What Are Low-Level Illusions
Visual illusions are very numerous
Known since Aristotle
- E.g., The ‘waterfall illusions’’
- Induces fatigues in neurons coding for motion
- This disturbs the balance with neurons coding for motion in the other direction, producing apparent motion in that direction
The Thather Illusion
Give examples of Geometric Illusions
- Muller-Lyer
- Ponzo
- Ebbinghaus
Illusion sensitivity differs between….
- Male versus female
- Mathematical scientists versus social scientists
- British versus Japanese
- Children versus adults
What does WEIRD stand for
- Western
- Educated
- Industrialised
- Rich
- Democratic
Unlike 88% of Earth’s Population
Yet much like most participants in psychology experiments
Study 1: Japan - What is the difference between East Asian Thought and Western thought?
East Asian Thought: Holistic, Intergrates Context
Western Thought: Analytic, Focuses on detal
How do Illusions differ between different groups?
- The illusion is stronger in women
- The illusion is stronger in Social Scientists than mathmaticians
- The illusion is stronger in Japan
- Young children don’t see it at all (and development relates to non-verbal IQ)
