Sensation: The process of detecting an environmental stimulus and converting it into neural activity.
Steps of Sensation
Stimulus Reception:
Sensory organs receive specific types of sensory stimulation (e.g., light for sight).
Transduction:
Specialized sensory receptor cells (e.g., rods and cones in the retina) convert stimuli into neural signals.
Signal Relay:
Neural signals pass through the thalamus (relay station for sensory systems) before reaching specialized brain areas:
Occipital lobe: Processes visual signals.
Temporal lobe: Processes auditory signals.
Parietal lobe: Processes touch and temperature.
Gustatory cortex: Processes taste.
Smell: Signals don't go through the thalamus; they pass through the amygdala (emotion) and hippocampus (memory).
Perception
Perception: The identification and interpretation of sensory stimuli.
Influenced by various characteristics:
Absolute Threshold: The minimum stimulus intensity needed for a receptor to react (e.g., lowest volume of a tone).
Just Noticeable Difference (JND): The minimum change in signal intensity detectable (e.g., easier to notice a 1 lb difference than a 1 lb difference in heavier weights).
Sensory Adaptation
Occurs when sensory receptor response decreases after continuous stimulation, reducing the perceived intensity of a stimulus (e.g., adapting to a persistent odor).
Can happen in any of the five major senses.
Perceptual Constancy
The tendency to perceive familiar objects as unchanging despite slight changes in stimulus (e.g., recognizing a shape, size, or color under varying conditions).
Perceptual Set
The tendency to perceive some stimuli and not others based on past experiences and expectations.
Can lead to processing errors.
Processing Types
Top-Down Processing: Uses prior knowledge to influence interpretation of sensory information (e.g., reading a sign with missing letters).
Bottom-Up Processing: The brain uses raw sensory data to create a perception.