Sensation & Perception Exam 1

Sensation detects a signal and transduces it into a conscious experience while perception gives meaning or purpose to detected sensations.

What is the difference between sensation and perception?

Sensory receptors

Where does sensation occur?

Brain

Where does perception occur?

Your brain must determine whether a neural signal was externally generated or just part of the “noise.”

What is the premise behind signal detection theory?

The relationship between stimulus and resulting sensation that says that just noticeable difference is a constant fraction of the comparison stimulus.

What does Weber’s law describe?

The relationship between stimulus and resulting sensation that says the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity.

What does Fechner’s law describe?

Doctrine of specific nerve energies stating that the nature of a sensation depends on which sensory fibers are stimulated, rather than how they are stimulated.

What does Muller’s doctrine describe?

Just noticeable difference vs. absolute threshold, method of constant stimuli, method of limits, and method of adjustment.

What are common ways to measure sensation?

Just noticeable difference

The smallest detectable difference between two stimuli, or the minimum change in a stimulus that enables it to be correctly judged as different from a reference stimulus.

Absolute threshold

Determine the minimum stimulus level required for perceptual detection.

How much larger does a stimulus have to be to be noticeably different vs can you tell if a stimulus is there or not.

What’s the difference between just noticeable difference and absolute threshold?

Method of limits

A method in which the particular dimension of a stimulus, or the difference between two stimuli, is varied incrementally until the participant responds differently.

Method of constant stimuli

A method in which many stimuli, ranging from rarely to almost always perceivable are presented one at a time. Random presentation.

Method of adjustment

A method of limits in which the participant controls the change in the stimulus.

Adaptation

Sensory receptors getting “used to” a continuous stimulus and detection ceases. Not under conscious control.

Habituation

The brain getting “used to” a continuous stimulus or using less neural resources to process repeated stimulation. Can be modulated by attention.

Orthonasal olfaction

Odorants travel through nostrils up to olfactory epithelium.

Retronasal olfaction

Exhaled odorants from mouth travel from back of mouth into upper nasal cavity to olfactory epithelium (this is flavor).

The perception of odors through the mouth while breathing and chewing that gives the experience of flavor.

How does retronasal olfaction contribute to flavor?

Shape-pattern theory and vibration theory. Shape-pattern theory is more widely accepted.

What are the theories about how olfactory receptors code for specific odors? Which one is more likely to be right?

By converging into spherical structures called glomeruli, where all neurons expressing the exact same odorant receptor project to the same specific glomerulus.

How do olfactory neurons organize themselves to represent odors at the olfactory bulb?

Olfactory epithelium, olfactory bulb, amygdala, hippocampus, primary olfactory cortex.

What major brain structures process smell?

No

Does smell go through the thalamus before it gets to the rest of the brain?

Semantic processing declines

How does age affect the sense of smell?

Women are better at odor identification, detection, and discrimination.

How does biological sex affect the sense of smell?

Smell does not improve memory accuracy for events over other modalities except emotional reactions.

How do smells impact memory?

Odorants enhance taste perception and create flavor.

How do taste and olfaction interact?

Fungiform papillae

Anterior tongue

Foliate papillae

Sides of tongue

Circumvallate

Posterior tongue

Filiform papillae

No taste

Ion channels

Where are salty and sour tastes transduced?

GPCRs

Where are bitter and sweet tastes transduced?

The evolutionary need for specificity versus general detection.

Why do some tastes get transduced via ion channels and others by GPCRs, and then some not at all?

Specific neurons respond to specific tastes.

What is the main theory regarding how different tastes are coded?

Miraculin doesn’t taste like anything by itself- it binds the receptor in neutral pH conditions but doesn’t activate it.

What is the basic idea behind how miracle berries work?

Ciliary body, iris, anterior chamber, pupil, cornea, lens, sclera, retina, macula, vitreous, artery, vein, optic nerve.

What are the major parts of the eye?

Rods

Periphery of retina, sensitive to low light.

Cones

More concentrated in fovea, involved in details and colors.

Process different aspects of the visual world and send parallel streams of information from the eye to the brain.

What are P and M ganglion cells for?

Hyperpolarizing (becoming more negative) and decreasing their release of the neurotransmitter glutamate.

How do rods and cones modulate their firing in response to stimulation by light?

The area of the cerebral cortex of the brain that receives direct inputs from the lateral geniculate nucleus, as well as feedback from other brain areas.

Primary visual cortex

Cortical magnification

The amount of cortical area devoted to a specific region in the visual field.

Lateral geniculate nuclei (LGNs)

A structure in the thalamus, part of the midbrain, that receives input from the retinal ganglion cells and has input and output connections to the visual cortex.