Sensation and Perception Flashcards
Sensory Receptors
•Specialized neurons that respond to specific types of stimuli
Occurrence of Sensation
- Sensation occurs when sensory information is detected by a sensory receptor
- Example – light that enters the eyes causes the chemical changes in cells that line at the back of the eye. These cells relay messages, in the form of action potentials, to the nervous system
- Not all sensation result in perception
Transduction
•The conversion from sensory stimulus energy to action potential
What are our senses?
- Vision
- Hearing (audition)
- Smell (olfaction)
- Taste (gustation)
- Touch (somatosensation)
- Vestibular Sense (balance)
- Proprioception and Kinesthesia (body position and movement)
- Nociception (pain)
- Thermoception (temperature)
Absolute Threshold
- Refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time
- Generally measured under incredibly controlled conditions in situations that are optimal for sensitivity
- May be influenced by motivation, experience and expectations
Difference Threshold (jnd)
- The minimum difference in stimulation that a person can detect 50% of the time.
- Changes depending on the stimulus intensity
Weber’s Law
•The difference threshold is a constant fraction of the original stimuli
Perception
•Refers to the way sensory information is organized, interpreted, and consciously experienced
Bottom-up Processing
•Refers to the fact that perceptions are built from sensory input
Top-down Processing
•Interpretations of those sensations that is influenced by our available knowledge, our experiences, and our thoughts
Sensory Adaption
•Individuals often don’t perceive stimuli that remain relatively constant over prolonged periods of time
Inattentional Blindness
•The failure to notice something that is completely visible due to lack of attention
Signal Detection Theory
•Ability to identify a stimulus when it is embedded in a distracting background
Muller-Lyer Illusion
- Lines appear to be different lengths although they are identical.
- Arrows at the ends of the lines may make the lines appear longer or shorter
Amplitude
•The height of a wave measured from the highest point on the wave (peak or crest) to the lowest point of the wave (trough)
Wavelength
- Length of a wave from one peak to the next
* Directly related to the frequency at a given wave form
Frequency
- Refers to the number of waves that pass a given point in a given time period
- Often expressed in terms of hertz (Hz), or cycles per second
- Longer wavelength will have lower frequencies, and shorter wavelength will have higher frequencies
Electromagnetic Spectrum
- Encompasses all the electromagnetic radiation that occurs in our environment
- Includes gamma rays, x-rays, ultraviolet light, visible light, infrared light, microwaves and radiowaves
Wavelength of Light (ROYGBIV)
- Our experience of Red is associated with longer wavelengths
- Greens have intermediate wavelengths
- Blue and violets are shorter in wavelengths
Amplitude of Light
- Associated with our experience of brightness or intensity of color
- Larger amplitudes appearing brighter
High-frequency Sound Waves
•Perceived as high-pitched sounds
Low-frequency Sound Waves
•Perceived as low-pitched sounds
Audible Range of Sound Frequencies
- Between 20Hz and 20000Hz
* Greater sensitivity to those frequencies that fall in the middle of this range
Amplitude of Sound Waves
- Higher amplitudes are associated with louder sounds
* Loudness is measured in terms of Decibels (dB)
Eye
•Major sensory organ involved in vision
Light Waves
•Transmitted across the cornea and enter the eye through the pupil
Cornea
- It is the transparent covering over the eye
- Serves as a barrier between the inner eye and the outside world
- Involved in focusing light waves that enter the eye
Pupil
- Is the small opening in the eye through which light passes
* When light levels are high, the pupil will constrict to reduce the amount of light that enters the light
Iris
- A thin, annular structure in the eye, responsible for controlling the diameter
- Colored portion of the eye
Lens
•Attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects
Fovea
- Part of the retina; light-sensitive lining of the eye
* Contains densely packed specialized photoreceptor cells, known as cones
Cones (Photoreceptor Cells)
- Light-detecting cells
- Specialized types of photoreceptors that work best in bright light conditions
- Sensitive to acute details
- Provide tremendous spatial revolution
- Directly involved in out ability to perceive colors
Rods
- Located throughout the remainder of the retina
- Specialized types of photoreceptors that work well in low light conditions
- Lack spatial resolution and color function
- Involved in our vision in dimly lit environments as well as our perception of movement on the periphery of our visual field
Night Blindnes
- A condition whereby rods do not transform light into nerve impulses as easily and efficiently as they should
- Difficulty seeing in dim light
Retinal ganglion cells
- Process visual information that begins as light entering the eye and transmit it to the brain via their axons, which are long fibers that make up the optic nerve.
- Over a million retinal ganglion cells; allow you to see as they send the image to your brain
Optic Nerve
•Carries visual information from the retina to the brain
Blind Spot
- An obscuration of the visual field.
* When light from a small object is focused on the blind spot, we do not see it
Optic Chiasm
- An x-shaped structure that sits just below the cerebral cortex at the front of the brain
- Information from the right visual field (which comes from both eyes) is sent to the left side of the brain and vice versa
Trichromatic Theory
•All colors in the spectrum can be produced by combining red, green, and blue
Opponent-process Theory
- According to the theory, colors is coded in opponent pairs
* Some cells of the visual system are excited by one of the opponent colors and inhibited by the other
Afterimage
•The continuation of a visual sensation after removal of the stimulus
Depth Perception (3-D space)
•We are able to describe things as being infront, behind, above, below or to the side of other things
Binocular Cues
•They rely on the use of both eyes
Binocular Disparity
•Slightly different view of the world that each of our eyes receives
Monocular Cues
•Cues that can be detected by one eye instead of two
Linear Perspective
•Refers to the fact that we perceive depth when we see two parallel lines that seem to converge in an image
Pinna
•The outer ear; visible part that protrudes from out heads
Middle Ear
•Contains three tiny bones known as the ossicles
Ossicles
- Malleus (or hammer)
- Incus (or anvil)
- Stapes (or stirrup)
Inner Ear
•Contains the semi-circular canals, which are involved in the vestibular sense and the cochlea
Cochlea
•A fluid-filled, snail-shaped structure that contains the sensory receptor cells of the auditory system
What causes movement in the three ossicles?
•Sound waves travel along the auditory canal and strike the tympanic membrane, causing it to vibrate. This vibration resulted in the movement of the three ossicles
What happens when the ossicles move?
- The stapes presses into a thin membrane of the cochlea known as the oval window.
- As the stapes presses into the oval window, the fluid inside the cochlea begins to move, which in turn stimulates hair cells, which are auditory receptor cells of the inner ear embedded in the basilar membrane
Basilar Membrane
•A thin strip of tissue within the cochlea
Activation of Hair Cells
- It’s mechanical process
* As hair cells become activated, they generate neural impulses that travel along the auditory nerve to the brain
Auditory Information
•Shuttled to the interior colliculus, the medial geniculate nucleus of the thalamus, and finally to the auditory cortex in the temporal lobe of the brain for processing
Temporal Theory of Pitch Perception
- Asserts that frequency is coded by the activity level of a sensory neuron
- A given hair cell would fire action potentials related to the frequency of the sound wave
Place Theory of Pitch Perception
•Suggests that different portions of the basilar membrane are sensitive of sounds to different frequencies
High-pitch Receptors
•Refers to the base of the basilar membrane as it responds best to high frequencies
Low-pitch Receptors
•Refers to the tip of the basilar membrane as it responds best to low frequencies
Auditory Localization
•Analogous to depth and scale perception for vision
Monaural Cues
- Relies on sounds reaching a single ear to constrain the set of possible sound sources
- The pinna is shaped asymmetrically so that incoming sound is distorted in a way that depends on the direction from which it arrives, especially the elevation
- The amplitude of a sound decreases quadratically with distance. If it is a familiar sound, then its distance can be estimated from the perceived amplitude.
- For distant sounds, a distortion of the frequency spectrum occurs because higher-frequency components attenuate more quickly than low-frequency components
- A powerful monaural cue is provided by the reverberations entering the ear as the sounds bounce around; this is especially strong in a room.
Binaural Cues
- Provide information on the location of a sound along a horizontal axis by relying on differences in patterns of vibration of the eardrum between our two ears
- If a sound comes from an off-center location, it creates two types of binaural cues: Interaural level differences and Interaural timing differences
Interaural Level Differences
•Refers to the fact that a sound coming from the right side of your body is more intense at your right ear than you left ear because of the attenuation of the sound wave as it passes through your head
Interaural Timing Differences
•Refers to the small difference in the time at which a given sound wave arrives at each ear
Congenital Deafness
•Refers to the people who are born deaf
Conductive Hearing Loss
- Refers to the people who lose their hearings due to age, genetic predisposition, or environmental effects
- Hearing problems are associated with a failure in the vibration of the eardrum and/or movement of the ossicles
- Solution: Hearing aids – amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely to occur
Sensorineural Hearing Loss
- It is when the hearing problem is associated with a failure to transmit neural signals from the cochlea to the brain
- Unable to be treated with hearing aids
- Solution: Cochlear implants – electronic devices that consists of a microphone, a speech processor, and an electrode array; receives incoming sound information and directly stimulates the auditory nerve to transmit information to the brain
What are the four basic groupings of taste?
- Sweet
- Salty
- Sour
- Bitter
Umani
- Fifth taste; a Japanese word that is roughly translated to yummy
- Associated with a taste for monosodium glutamate
Saliva
•Dissolve molecules from the food and beverages we consume
Taste Receptors
•Allow interaction with the molecules from the food and beverages on our tongue, mouth, and throat
Taste Buds
•Formed by groupings of taste receptor cells with
hair-like extensions that protrude into the central pore of the taste bud
•A life cycle of 10 days to 2 weeks
Where will the taste information be transmitted to?
•It will be transmitted to the medulla, thalamus, limbic system, and to the gustatory cortex, which is tucked underneath the overlap between the frontal and temporal lobes
What is the location and the purpose of olfactory receptor cells
- Located in a mucous membrane at the top of the nose
- Serve as the sites for odor molecules dissolved in the mucus to interact with the chemical receptors
- Once an odor molecule has bound on a given receptor, chemical changes within the cell result in signals being sent to the olfactory bulb
Olfactory Bulb
- A bulb-like structure at the tip of the frontal where the olfactory nerves begin
- Information is sent to regions of the limbic system and to the primary olfactory cortex, which is located near the gustatory cortex
Pheromonal Communication
- Release chemical messages, known as pheromones
* Involves in providing information about the reproductive status of a potential mate
Meissner’s Corpuscles
•Respond to pressure and lower frequency vibrations
Pacinian Corpuscles
•Detect transient pressure and higher frequency vibrations
Merkel’s Disks
•Responds to light pressure
Ruffini’s Corpuscles
•Responsible for the sensation of the stretch of your skin, sustained pressure on the skin, and the perception of heat.
Thermoception
•The sensation and perception of temperature, or more accurately, temperature differences inferred from heat flux
Nociception
•The sensory nervous system’s response to certain harmful or potentially harmful stimuli
Where does sensory information travels to?
- Sensory information collected from the receptors and free nerve endings travel up to the spinal cord
- Transmitted to regions of the medulla, thalamus, and ultimately to somatosensory cortex, which is located in the post-central gyrus of the parietal lobe
Pain
- Pain is an unpleasant experience that involved both physical and psychological components
- Considered to be neuropathic or inflammatory in nature
Inflammatory Pain
•Refers to pain that signals some type of tissue damage
Neuropathic Pain
- Refers to pain that results from damage to neurons of either the peripheral or central nervous system
- Pain signals that are sent to the brain are exaggerated
Treatment Options for Pain Relief
- Relaxation therapy
- Analgesic medications
- Deep brain stimulation
*Effective treatment option for a given individual will depend on a number of considerations, including the severity and persistence of the pain as well as any medical or psychological conditions
Congenital Insensitivity to Pain
- Individuals who are born without the ability to feel pain
* Often suffer significant injuries; shorter life expectancy
Vestibular Sense
- Contributes to our ability to maintain balance and body posture
- Fluid-filled and have hair cells, similar to the ones found in the auditory system, which respond to movement of the head and gravitational forces
- When these hair cells are stimulated, they send signals to the brain via the vestibular nerve
Vestibular System
•Collects information critical for controlling movement and the reflexes that move various parts of our bodies to compensate for changes in body position
Proprioception and Kinesthesia
- Proprioception – perception of body position
- Kinesthesia – perception of the body’s movement through space
- Both interact with information provided by vestibular system
- Travels to the brain via the spinal column
- Several cortical regions in addition to the cerebullum receive information from and send information to the the sensory organs of the proprioceptive and kinesthetic systems
Figure-ground Relationship
- Refers to the tendency to segment our visual world into figure and ground
- Our perception can vary tremendously, depending on what is perceived as ground and what is perceived as figure
Principle of Proximity
•Asserts that things that are close to on another tend to be grouped together
Law of Continuity
•Suggests that we are more likely to perceive continuous, smooth flowing lines rather than jagged, broken lines
Principle of Closure
•States that we organize our perceptions into complete objects rather than a series of parts
Perceptual Hypotheses
- Educated guesses that e make while interpreting sensory information
- Informed by a number of factors, including our personalities, experiences, and expectations
