exam 3 Flashcards
Environmental Stimuli
- All available stimuli for an observer
- EX: walking through the woods
Attended Stimuli
- Stimuli that are the point of focus for the observer.
- EX: moth on a tree
Stimulus on the Receptors
- “image” of stimulus on the receptors cells.
- EX: image on person’s retina (image of moth)
Transduction
- The transformation of an environmental stimulus.
- light in; electricity out
Early Neural Processing
- Interconnected neurons that propagate the electrical signal from receptor cells throughout the brain.
- EX: signals in neurons
Perception
- conscious sensory experience
- EX: someone perceives something on the tree
Recognition
- Ability to place objects in categories that provide meaning.
- EX: person realizes it is a moth on the tree
Action
- motor activities that occur in reference to the perceived and object
- EX: person walks toward to the moth that they see
Sensation
- Automatic but unaware collection of information through the sensory organs.
Perception
- Conscious sensory experience, high-level processing, usually.
Sensory Receptors
- specialized cells (receptors) that transduce (convert) sensory energy into neural activity.
- Vision, Auditory, Somatosensory, Taste & Olfaction
Vision
Light energy ➡️ chemical energy ➡️ Neural Activity
Auditory
Air Pressure ➡️ Mechanical Energy ➡️ Normal Activity
Somatosensory
Mechanical energy ➡️ Neural Activity
Taste & Olfaction
Chemical Molecules ➡️ Neural Activity
Synesthesia
A perceptual phenomenon in which *stimulation of one sensory pathway triggers experiences in a second sensory or cognitive pathway. *
Receptor Density
- Important in determining the sensitivity of a sensory system.
EX: more tactile receptors on the fingers as compared to the arm - Determine the special abilities of many animals
EX: olfactory ability of dogs
Perception & sense of reality are products of evolution..
- sensory systems provide a survival advantage
- Type of energy in the environment determines which senses have developed
- animal sense ls are specialized for certain kinds of energy in the environment
Functional Anatomy of the Visual System
- optics, structure of the eye, and image information
- Retina, photoreceptors (rods & cones)
- Receptive fields
Refraction
- necessary to focus light rays, accomplished by the cornea and lens.
Accommodation (refraction)
- The process in which the lens changes its shape, thus altering its refractive power.
Problems with focusing / refraction
- Myopia
- Hyperopia
Myopia
- when the light entering the eye is focused in front of the retina and distant objects cannot be seen sharply
- NEARsightedness
Hyperopia
- when light entering the eye is focused behind the retina
- FARsightedness
Retina
contains 2 types of photoreceptors
- Rods
- Cones
Rods
- Sensitive to low levels of light (dim light)
- used mainly for night vision
- one type of photopigment only
- more numerous than cones
Cones
- Highly responsive to bright light
- Specialized for color and high visual acuity
- located mostly in the fovea
- three photopigments
Types of neurons in the retina
- Photoreceptors
- Bipolar cells
- Retinal ganglion
- Horizontal cells
- Amacrine cells
Bipolar cells
- receives input from photoreceptors
Retinal Ganglion cells
- gives rise to the optic nerve
Horizontal cells
- Link photoreceptors and bipolar cells
Amacrine cells
- Link bipolar cells and ganglion cells
Structure of the eye
- Cornea
- Iris
- Lens
- Retina
cornea
- clear outer covering
Iris
- Opens and closes to allow more or less light in
- the hole in the iris is called the PUPIL
Lens
- Focuses light
- Bends to accommodate near and far objects.
Retina
- Where light energy initiates neural activity.
Receptive Fields
- the sensory area that influences the electrical activity of sensory neurons (or follow up interneurons)
- include inputs from multiple receptors
Excitatory
- ON
- Center
- Inhibitory Surround
Inhibitory
- OFF
- center
- excitatory surround
ON-center ganglion cells
- Excited by light on their center
- Inhibited by light in their surround
OFF-center ganglion
- Inhibited when light is in center
- Excited when light is in surround
Topographical Mapping
- close by areas in the visual field are “mapped” onto close by areas in cortex.
Processing Shape in V1
- each cell receives input from multiple RGC’s and have much larger receptive fields
- cells behave like orientation detectors
(excited by bards of light oriented in particular directions) - simple cells
(receptive field with a rectangular on-off arrangement)
Dorsal Visual Stream
- pathway that originates in the occipital cortex and projects to the PARIETAL cortex
- the “how” or “where” pathway.
- How action is to be guided toward objects
Ventral Visual Stream
- Pathway that originates in the occipital cortex and projects to the TEMPORAL cortex
- the “what” pathway
- identifies what an object is
Processing shape in the Temporal Cortex
- cells are maximally excited by complex visual stimuli (faces or hands)
Three types of Cone Pigments Absorptions
- BLUE (short wavelength)
- GREEN (middle wavelength)
- RED (long wavelength)
Trichromatic Theory
- explanation of color vision based on the coding of 3 primary colors (Red, Green, & Blue)
- the color we see is determined by the relative responses of the different cone types.
- can explain different types of color blindness
Opponent-Process Theory
- explanation of color vision that emphasizes the importance of the opposition colors (Red vs. Green / Blue vs. Yellow)
- occurs in retinal ganglion cells
Function of Hearing
- identification of sounds
- localization of sounds
- communication
loudspeakers produce sound by….
- The diaphragm of the speaker MOVES OUT, pushing air molecules TOGETHER
- The diaphragm also MOVES IN, pulling air molecules APART.
- the cycle of this process creates ALTERNATING high & low pressure regions that TRAVEL through air.
Frequency
- number of cycles within a given time period
- measured in Hertz (Hz)
- perception of pitch is related to frequency
what range is human hearing
20 - 20,000 Hz
Fundamental Frequency
- the rate at which the complex waveform pattern repeats
- the lowest frequency component of a complex periodic sound
Overtones (Harmonics)
- set of higher frequency sound waves that vibrate at whole-number (integer) multiples of the fundamental frequency.
- multiples of the fundamental frequency
Timbre
The psychological sensation by which a listener can judge that 2 sounds with the same loudness and pitch are dissimilar
Three parts of Ear
- Outer ear (captures sound)
- Middle ear (transformer)
- Inner ear (biological amplifier & analyzer)
Middle Ear
- Tympanic membrane (ear drum)
- ossicles of the middle ear transmits vibrations of the tympanic membrane to the inner ear
- important for well-being in regard to air pressure.
- transforms air pressure fluctuations into basilar membrane movements.
Ossicles
The three bones of the middle ear transmit the vibrations of the tympanic membrane to the inner ear
Tympanic Membrane
- The eardrum
- a thin sheet of skin at the end of the outer ear canal. Vibrates in response to sound.
Inner Ear
- Cochlear canals & membranes
- cochlea
- middle canal
Cochlea
- Spiral structure of the inner ear filled with watery fluids in three parallel canals
Middle Canal
- sandwiched between the tympanic and vestibular canals. contains the basilar membrane with the organ of Corti
Organ of Corti
- A structure on the basilar membrane that features receptor cells (hair cells) arranged along one inner row and three outer rows.
- inner ear
Stereocilla
- Hairlike extensions on the tips of hair cells in the cochlea that initiate the release of neurotransmitters when they are flexed.
- inner hair cells transform vibrations into action potentials
Bèkèsys’ Place Theory of Hearing
- Frequency of sound is coded by the place along the cochlear partition where the traveling wave has its greatest displacement
