Sensation and Perception Overview

Sensation and Perception

• Stimulus: Any physical energy source that triggers a response in a sensory organ.
• Sensation: The reception of physical energy by a sensory organ.
• Perception: The interpretation, analysis, and integration of stimuli, done by sensory organs and the brain.
• Stimulus energy => Sensory receptors => Neural impulses => Brain (visual, auditory, olfactory areas) (e.g., light, sound, smell => eyes, ears, nose => brain).

Brain and Perception

• Different brain areas process different senses.
• Even within a specific area (e.g., visual cortex), different sub-areas have specialized functions.

Critical Role of Sensation and Perception

• The outside world provides overwhelming information.
• Our sensory and perceptual systems select and prioritize relevant and significant information for the brain.
• Example: visual perception.

Visual Perception

• The human visual system processes a limited range of wavelengths.
• Retina: A layer of photoreceptor cells.
• Fovea (fovea centralis): A small pit in the retina providing high visual acuity.

Structure of Retina

• Cones: Specialized for color vision in bright light..
• Rods: Specialized for black and white vision in dim light.

Colour Perception

• The activity of a single type of cone is insufficient to identify color.
• Comparing the activity of the three cone types is necessary for color perception.
• The brain actively processes color information.

Colour Constancy

• The ability to perceive objects as consistently colored even under changing lighting conditions.

Gestalt Principles

• Gestalt psychologists emphasize integrating information into meaningful wholes.
• Perception isn't just the sum of individual parts; it's a holistic process.

Sensation-Perception-Cognition

• Sensation provides basic information to the brain.
• Perception processes this information.
• Cognition further interprets and elaborates on the information.

Perceiving Depth

• Depth perception enables us to see the world in 3D and judge distances.
• A retinal image is 2D, but the world is 3D.

Depth Perception Cues (Based on knowledge and assumptions of the world)

• Relative size
• Light and shadow
• Interposition (overlap)
• Texture

Size Constancy

• Our perception of object size remains consistent even if their distance varies.
• This is another form of world knowledge aiding perception.
• It can help us determine depth.

Summary

• Sensation provides raw data.
• Perception processes the data.
• Cognition elaborates on the processed information.
• Ambiguity exists at all stages of this process.

Explore the fundamental concepts of sensation and perception in this quiz. Understand how sensory organs respond to stimuli and how the brain interprets this information. Test your knowledge on the critical role of different brain areas in processing sensory information.