Psychology Sensory Systems Overview

Study Notes

Absolute threshold: Minimum stimulus energy for sensation. Examples include a candle flame visible 30 miles away (vision), a watch ticking 20 feet away (hearing), a teaspoon of sugar in 2 gallons of water (taste), a bee's wing falling on the cheek from 1 cm (touch), and one drop of perfume in a 3-room apartment (smell).
Difference threshold (Just Noticeable Difference): Minimum difference between two stimuli for perception of difference in intensity.
Signal Detection Theory: Incorporates individual decision-making and considers "noise" in the perception process.
Sensory Adaptation: Changes in sensitivity to stimuli over time; includes sensitization (increased sensitivity) and desensitization (decreased sensitivity).

Light enters the eyes, reaching the retina.
The retina converts light into neural signals.
The process involves the pupil and lens focusing light onto the retina.
Neural signals travel from the retina to the primary visual cortex in the brain for interpretation.

Myopia (nearsightedness): Difficulty seeing distant objects clearly.
Hyperopia (farsightedness): Difficulty seeing nearby objects clearly.
Presbyopia: Age-related loss of lens flexibility, affecting focus at varying distances (typically begins around 38-46 years old).
Strabismus (cross-eyed): Inability of both eyes to focus on the same point simultaneously.
Astigmatism: Distorted images due to abnormal lens curvature.
Color blindness: Ranges from monochromacy (seeing only light and dark) to partial color blindness (dichromacy, typically red-green or blue-yellow deficiency, often sex-linked).

Conduction deafness: Damage to middle ear structures (eardrum or bones), impacting sound wave transmission. Often helped by hearing aids.
Sensorineural deafness: Damage to hair cells in the cochlea (cannot regenerate). May result in sensitivity to certain pitches more than others.
Stimulation deafness: Hair cell damage due to exposure to very loud sounds.

Gaseous particles stimulate olfactory mucosa receptor cells.
Signals are transmitted via olfactory bulbs to the amygdala (involved in emotional responses to smell) and thalamus (relaying signals to the cortex).
Anosmia: Loss of smell for specific odors, indicating damage to certain olfactory receptors. The nose detects basic odors like flowery, musky, ethereal, pungent, putrid, and burnt.

Liquid substances stimulate taste receptors (taste buds) in papillae.
Primary tastes include sweet, sour, bitter, salty, and umami. Different combinations of these tastes create a wide range of flavor perceptions.