Perception & Cognition Psychology Flashcards
Stimulus
- Any passing source of physical energy that produces a response in a sense organ
Sensation
- Activation of the sense organs by a source of physical energy
Perception
- Sorting out, interpretation, analysis and integration of stimuli carried out by the sense organs and brain
Sensation & Perception process
- Stimulus energy: Light, sound, smell etc
- Sensory receptors: Eyes, ears, nose etc
- Neural impulses
- Brain: Visual, auditory, olfactory areas
How many senses
- 8
Brain & Perception
- Different areas of the brain are responsible for processing different senses
- Even within one area (visual cortex) different subareas function for different purposes
Visual Perception
- Human visual system can only process a certain range of wavelengths
Structure of the eye
- Retina: a layer of photoreceptor cells
- Fovea (fovea centralis): a small pit in the retina; provides the most accuracy in vision
Structure of Retina
- Cones: sensitive to colours; used under light
- Rods: used in dim light; black-and-white perception
How many cones types are there in homo sapiens
- 3
Cones colpurs
- Blue: short-wavelengths cones
- Green: medium-wavelength cones
- Red: long-wavelength cones
Cones
- Activity of a single cone (type) is not sufficient to identify colour
- Colour perception involved comparison in activity between the three cone types
From Cones to Brain: Convergence
- Comparison between cone types require some way of monitoring and comparing activity of more than one cell at a time
- So there is some cells that receive input from more than one cone
From Cones to Brain: Convergence: take place
- Occurs in retina and in visual cortex
Colour constancy
- Perceiving objects as having consistent colour, even if changing illumination alters the wavelengths
reflected by the objects
Gestalt
- Organised whole
- Gestalt psychologists (early 20th century) emphasised our tendency to integrate pieces of information into meaningful wholes.
- Perception is not just the sum of all parts.
Gestalt Principles
- Similarity
- Proximity
- Closure
- Continuity
Perception
- Processing information from senses
Cognition
- Elaboration of information
Perception & Cognition stage
- Sensation > perception > cognition
sensation > perception: bottom-up (stimulus-driven)
perception > cognition
top-down (knowledge-driven)
Perceiving depth
- We need to construct a 3D world from a 2D retinal image
- Intrinsically difficult, complex task
Depth Perception
- Recovering size and depth from a 2D retinal image cannot be explained by sensation alone.
- Requires internal cognitive processing to recover perception.
- Based on knowledge and assumptions about the world.
Size Constancy
- Knowledge/understanding of world to aid perception.
- Things don’t tend to change in physical size.
- Size cues for depth perception
Visual Illusions
- Ponzo illusion: Depth cues (size constancy) can cause (physical) size illusions
Ames Room Illusion
- Using false cues for depth to alter perception of size
- Different size people in same room
Illusory Contours
- Cut shapes making it look like there is another shape