General Psychology - Unit 2
General Psychology - Unit 2
General Psychology - Unit 2
Prepared by
Ms. Shiva Priya A
Sensation
• What is
1. Stimuli/input
2. Pathways to receive stimuli
3. Sensory receptors
4. Sensation
• Concepts in sensation
1. Transduction
2. Sensory thresholds & Absolute thresholds
3. Habituation & Sensory Adaptation
Transduction
Synesthesia
Sensory Thresholds
• The degree of difference that • The minimum level of • The level of energy
must exist to detect the energy required to is below the
difference between the detect the input/ threshold yet strong
stimuli stimuli enough to activate
• Found by Earnst Weber • Found by Fetchner the sensory
receptors resulting
in subconscious
processing.
Signal detection Theory
Habituation and Sensory Adaptation
Vision – Light and Eye
• Light enters the eye through the cornea and pupil. The iris controls the size of
the pupil. From the pupil, light passes through the lens to the retina, where it is
transformed into nerve impulses. The nerve impulses travel to the brain along the
optic nerve.
• Cornea – Curve structure that causes “refraction” (Light bends as it passes
through substances of different densities, through a process known as refraction).
• Aqueous humor- Watery layer that nourishes eye.
• Pupil – Small hole through which light passes
• Iris – Coloured round muscles around the pupil
• Lens – Positioned behind iris that helps in focus by ‘visual accommodation’
process (the change in the thickness of the lens as the eye focuses on objects
that are far away or close.).
Vision – Structure of Eye
• The variation in thickness allows the lens to project a sharp image on the retina.
• People lose this ability as the lens hardens through aging, a disorder called ‘presbyopia’.
• Vitreous Humor – Jelly like fluid similar to aqueous humor that nourishes the eye and
gives shape.
• Retina – Last stop where light reaches. It has Bipolar cells, Ganglion Cells, Photoreceptor
Cells (Cones & Rods)
• Rods - visual sensory receptors found at the back of the retina, responsible for noncolor
sensitivity to low levels of light.
• Cones - visual sensory receptors found at the back of the retina, responsible for color
vision and sharpness of vision.
• Blind Spot - area in the retina where the axons of the three layers of retinal cells exit the
eye to form the optic nerve; insensitive to light/Stimuli.
Hearing - Structure of Ear
• Structure of Ear - https://www.youtube.com/watch?
v=1jWGLsjpkbI
Hearing – Perceiving the pitch - Theories
• Place Theory - theory of pitch that states that different pitches are
experienced by the stimulation of hair cells in different locations on the
organ of Corti.
• Frequency theory - theory of pitch that states that pitch is related to the
speed of vibrations in the basilar membrane.
• Volley principle - theory of pitch that states that frequencies from about
400 Hz to 4000 Hz cause the hair cells (auditory neurons) to fire in a volley
pattern, or take turns in firing.
Hearing – Types of hearing impairments
• Tongue has –
• Taste buds/Taste receptor cells – neurons present in mouth.
• Little bumps called ‘Papillae’ – covered by taste buds.
• Five types of taste –
• Sweet
• Sour
Hans Henning
• Salty
• Bitter
• Umami (Brothy) Lindemann
• The taste information is sent to the ‘gustatory cortex’, found in the front part
of the insula and the frontal operculum. These areas are involved in the
conscious perception of taste.
Olfactory/Scent - Nose
• Size
• Shape
• Brightness
Gestalt principles of grouping