Chapter 2: Sensation and Perception Flashcards
Define sensation.
Aligns with transduction, which is the conversion of physical, electromagnetic, auditory, and other information from our internal and external environment to electrical signals in the nervous system
What performs sensation?
Performed by receptors in the PNS, which forward the stimuli to the CNS in the form of action potentials and neurotransmitters
What is the term that best defines a raw signal?
Sensation
Define perception.
Refers to the processing of information to make sense of its significance.
Define ganglia.
Collections of neuron cell bodies found outside the CNS
How do sensory receptors transmit information?
Receive stimulus, and transmit the data to the CNS through sensory ganglia
What happens once transduction occurs?
Electrochemical energy is sent along neural pathways to various projection areas in the brain, which further analyze sensory input
What do photoreceptors respond to?
Electromagnetic waves in the visible spectrum (sight)
What do hair cells respond to?
Movement of fluid in the inner ear structures (hearing, rotational and linear acceleration)
What do nociceptors respond to?
Painful or noxious stimuli (somatosensation)
What do thermoreceptors respond to?
Changes in temperature (somatosensation)
What do osmoreceptors respond to?
Osmolarity of blood (water homeostasis)
What do olfactory receptors respond to?
Volatile compounds (smell)
What do taste receptors respond to?
Dissolved compounds (taste)
Define threshold.
The minimum amount of a stimulus that renders a difference in perception
What are the three types of thresholds?
- Absolute threshold
- Threshold of conscious perception
- Difference threshold
Define the absolute threshold.
Minimum of stimulus energy that is needed to activate a sensory system (at which a stimulus will be transduced and converted into action potentials)
What kind of threshold is this? We’re talking about how bright, loud, or intense a stimulus must be before it is sensed.
Absolute threshold
Define the threshold of conscious perception. What is it also called?
- Stimulus below the threshold of conscious perception arrives at the CNS, but does not reach the higher-order brain regions that control attention and consciousness
- Subliminal perception
Define the difference threshold. What is it also called called?
- Minimum difference in magnitude between two stimuli before one can perceive this difference
- Just-noticeable difference
What does Weber’s law state?
- There is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of original stimulus.
- For higher-magnitude stimuli, the actual difference must be larger to produce a jnd
What does the signal detection theory state?
Focuses on the changes in our perception of the same stimuli depending on both internal (psychological) and external (environmental) context
Define response bias.
Refers to the tendency of subjects to systematically respond to a stimulus in a particular way due to nonsensory factors.
What are catch trials? What are noise trials?
Catch trials: signal is presented
Noise trials: signal is not present
What are the four possible outcomes for trials in basic signal detection experiments?
1) Hits: correctly perceives the signal
2) Misses: fails to perceive a given signal
3) False alarm: perceive a signal when none was given
4) Correct negatives: correctly identifies that no signal was given
What is the pathway for a stimulus to reach conscious perception?
Sensory receptor, afferent neuron, sensory ganglion, spinal cord, brain (projection areas)
How does sensory adaptation affect the difference threshold?
Adaptation generally raises the difference threshold for a sensory response; as one becomes used to small fluctuations in the stimulus, the difference in stimulus required to evoke a response must be larger
Which lobe is entirely devoted to vision?
Occipital lobe
What is the thick structural layer of the eye? What portion does it not cover?
- Sclera, or the white of the eye
- Does not cover the cornea
The eye is supplied with nutrients by two sets of blood vessels. What are they?
- Choroidal vessels: complex intermingling of blood vessels between the sclera and the retina
- Retinal vessels
What is the innermost layer of the eye? What does it contain?
- Retina
- Contains the photoreceptors that transduce light into electrical information the brain can process
What does the cornea do? Where is it located?
- Located in the front of the eye
- Gathers and focuses incoming light
Where does the anterior chamber lie? Where does the posterior chamber lie?
Anterior chamber: in front of the iris
Posterior chamber: between the iris and the lens
What is the colored part of the eye?
Iris
What are the two muscles in the iris? Which nervous systems are they associated with?
Dilator pupillae: sympathetic
Constrictor pupillae: parasympathetic
What produces the aqueous humor that bathes the front part of the eye? Where does it drain?
- Ciliary body
- Canal of Schlemm
Where does the lens lie? What does it do?
- Lies right behind the iris
- Helps control the refraction of the incoming light
Contraction of the ciliary muscle, a component of the ciliary body, is under the control of which nervous system?
Parasympathetic
As the ciliary muscle contracts, it pulls on what? What does that do? What is this phenomenon?
- Pulls on suspensory ligaments
- Changes the shape of the lens
- Accommodation
What lies behind the lens and supports the retina?
Vitreous
Where does the retina lie? What is its main function?
- In the back of the eye; screen that consists of neural elements and blood vessels
- Convert incoming photons of light to electrical signals