Pillar 1: Sensation and Perception

Sensation

The process by which sensory receptors detect environmental stimuli and convert them into neural signals (e.g., rods in your eyes detecting light)

Perception

How your brain organizes, interprets, and gives meaning to those sensory signals, often influenced by context and expectations

Absolute Threshold

The minimum level of stimulus intensity needed for detection 50% of the time, such as candlelight seen 30 miles away

Difference Threshold

(Just Noticeable Difference, JND): The smallest difference between two stimuli that can be reliably detected; follows Weber’s Law (difference is a constant fraction of original stimulus)

Signal-Detection Theory

This framework assesses how we discern signals from noise, noting that detection is influenced by both stimulus intensity and subjective criteria—leading to hits, misses, false alarms, or correct rejections

Sensory Adaptation

A reduction in sensitivity when a stimulus remains constant—like tuning out a ticking clock after awhile—helping us focus on novel information

Rods

Photoreceptors in the retina highly sensitive to low light, but not color; good for night vision

Cones

Photoreceptors concentrated in the fovea, active in bright light, responsible for color vision

Blind Spot

The point where the optic nerve exits the eye; no photoreceptors exist there, but we don’t notice it due to binocular vision and brain “filling in”

Kinesthesia

Sense of body movement and limb position via receptors in muscles, tendons, and joints

Vestibular Sense

Detects head movement and balance via hair cells in the semicircular canals, utricle, and saccule of the inner ear

Prostaglandins

Biochemical compounds released by damaged tissue; they sensitize nociceptors, heightening the sensation of pain.

Nociceptors

Pain receptors (a type of free nerve ending) that respond to potentially harmful mechanical, thermal, or chemical stimuli

Vision

light

Hearing (Audition)

sound waves

Smell (Olfaction)

airborne chemicals

Taste (Gustation)

soluble chemicals on the tongue

Touch (Somatosensation)

pressure, vibration, temperature, and pain