Behaviorial Sciences 2: Sensation and Perception

Sensory Receptors

Sensory nerves that respond to stimuli.

Sensory Ganglia

Collection of cell bodies outside the CNS.

Projection Areas

Areas in the brain that analyze sensory input.

Absolute Threshold

The min of stimulus energy that will activate a sensory system.

Threshold of Conscious Perception

The minimum stimulus energy that will create a signal large enough in size and long enough in duration to be brought into awareness.

Difference Threshold

The min difference in magnitude between two stimuli before one can perceive this difference.

Weber’s Law

Just Noticeable Difference (JND) for a stimulus is proportional to the magnitude of the stimulus.

Signal Detection Theory

Refers to the effects of nonsensory factors, such as experiences, motives, and expectations on perception of stimuli. Accounts for response bias.

Adaptation

Refers to a ↓ or ↑ in sensitivity to a stimulus.

Cornea

Gathers and filters incoming light.

Iris

Controls size of pupil. Colored part of eye. Divides front of the eye into the anterior & posterior chamber. It contains 2 muscles, the dilator and constrictor pupillae.

Lens

Refracts incoming light to focus it on the retina.

Aqueous Humor

Produced by the ciliary body. Nourishes the eye and gives the eye its shape. Drains through the canal of Schlemm.

Retina

Rods: Detect light / dark. Contain rhodopsin. Cones: Color. Short / medium / long. Cones are in the fovea, which is part of the macula. Pathway from retina: Rods/Cones → bipolar cells → ganglion cells → optic nerve.

Retinal Disparity

Space between eyes; allows for binocular vision and depth.

Horizontal & Amacrine Cells

Integrates signals from ganglion cells and performs edge-sharpening.

Support

Vitreous on inside. Sclera and choroid on outside.

Parallel Processing

Color, form, and motion at same time.

Magnocellular Cells

Motion. High temporal resolution.

Parvocellular Cells

Shape. High spatial resolution.

Outer Ear

Pinna (auricle), external auditory canal, tympanic membrane.

Middle Ear

Connected to nasal cavity by Eustachian tube. Ossicles: Acronym MIS and HAS. Malleus: Hammer Incus: Anvil Stapes: Stirrup. Footplate of stapes rests in the oval window of cochlea.

Inner Ear

Bony Labyrinth: Filled with perilymph. Membranous Labyrinth: Filled with endolymph. Membranous labyrinth consists of cochlea (sound), utricle & saccule (linear acceleration) and semicircular canals (rotational acceleration & balance).

Superior Olive

Localizes sound. Located in brain stem.

Inferior Colliculus

Startle reflex. Also used by both eyes and ears in the vestibulo-ocular reflex which keeps the eyes fixed on a single point as the head rotates.

Smell

The detection of volatile or aerosolized chemicals by the olfactory chemoreceptors (olfactory nerves) in the olfactory epithelium. Smell info bypasses the thalamus.

Pheromones

Chemicals given off by animals that have an effect on social foraging, and sexual behavior.

Taste

The detection of dissolved compounds by taste buds in papillae. Sweet/sour/salty/bitter/umamai.

Somatosensation

Refers to the four touch modalities: Pressure, vibration, pain, temperature.

Two-Point Threshold

Minimum distance necessary between 2 points of stimulation on the skin such that the points will be felt as two distinct stimuli.

Physiological Zero

The normal temp of skin to which objects are compared to.

Nociceptors

Pain reception. Gate theory of pain. ↓JND for pain.

Kinesthetic Sense

Proprioception

Top-Down Processing

The recognition of an object by memories and expectations. Little attention to detail. Uses background knowledge.

Bottom-Up Processing

Recognition of objects by feature detection. Details → whole. Not influenced by background knowledge.

Gestalt Principles

Proximity, similarity, continuity, closure. All are governed by the Law of Prägnanz.

Visual Pathway

Eye —> optic nerves —> optic chasm —> optic tracts —> lateral geniculate nucleus (LGN) —> visual radiations —> visual cortex

Auditory Pathway

Cochlea —> vestibulocochlear nerve —> medial geniculate nucleus (MGN) —> auditory cortex