Sensation and Perception

• Sensory Receptors

Specialized neurons that respond to specific types of stimuli

• Sensation

When sensory information is detected by a sensory receptor

• Transduction

Conversion from sensory stimulus energy to action potential

• Absolute Threshold

The minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time

• Subliminal messages

Messages that are presented below the threshold for conscious awareness

• Just noticeable difference (JND) (AKA difference threshold)

How much difference in stimuli is required to detect a difference between them

• Webers Law

The difference threshold is a constant fraction of the original stimulus

• Perception

The way sensory information is organized, interpreted, and consciously experienced

• Bottom-up processing

Sensory information from a stimulus in the environment driving a process

• Top-Down processing

Knowledge and expectancy driving a process (generally goal directed, slow, deliberate, effortful, and under your control)

• Sensory adaptation

We often don’t perceive stimuli that remain relatively constant over prolonged periods of time

• Attention

plays a significant role in determining what is sensed versus what is perceived

• Inattentional blindness

Failure to notice something that is completely visible because the person was actively attending to something else and did not pay attention to other things

• Signal Detection theory

Ability to identify a stimulus when It is embedded in a distracting background

• Amplitude

Distance from the center line to the top point of the crest or the bottom point of the trough.

• Wavelength

Refers to the length of a wave from one peak to the next. Directly related to frequency.

• Frequency

The number of waves that passes a given point in a given time period and is often expressed in terms of Hertz (hz) or cycles per second.

• Long Wavelengths

Low frequency

• Short Wavelengths

High frequency

• Visible spectrum

Portion of the larger electromagnetic spectrum that we can see

• Electromagnetic Spectrum

Encompasses all of the electromagnetic radiation that occurs in our environment and includes gamma rays, x-rays, UV light, visible, infrared light, microwaves, and radio waves

• Visual spectrum for humans

Wavelengths that range from 380 to 740 nm (very very small)

• ROYGBIV

Listing of colors that puts them in order from longest wavelength to shortest

• High Frequency sound waves

High pitched sounds

• Low Frequency sound waves

Low pitched sounds

• Audible range of sound frequencies

between 20 and 20000 Hz

• High Amplitude

Loud sound

• Low Amplitude

Soft sound

• Decibels (dB)

Units for sound

• Cornea

Transparent covering over the eye. Involved in focusing light waves that enter the eye.

• Pupil

Small opening in the eye through which light passes, and the size can change based on light levels as well as emotional arousal.

• Low Light Levels

Pupil dilates

• High Light Levels

Pupil constricts

• Iris

Colored part of the eye. Connected to muscles that control the dilation of the pupil.

• Lens

Curved, transparent structure that serves to provide additional focus. 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, contains densely packed photoreceptor cells (aka cones). Lens will focus on this when images are focused perfectly.

• Photoreceptor cells

Light-Detecting cells.

• Cones

Specialized types of photoreceptor cells that work best in bright light conditions and are directly involved in our ability to perceive color. Provide tremendous spatial resolution.

• Pupil

Specialized photoreceptors located throughout the remainder of the retina. Work well in low light conditions and are involved in our vision in dimly lit environments as well as in our perception of movement.

• Optic Nerve

Carries visual information from the retina to the brain

• Blind Spot

Even when light from a small object is focused on the blind spot, we do not see it. Blind spots from each eye do not overlap, and our visual system fills in the blind spot so that although we can't respond to visual info, we are not aware the info is missing.

• Pupil

Where the optic nerve from each eye merges and sends info to each other. X-Shaped structure that sits just below the cerebral cortex at the front of the brain.

• Trichromatic Theory of Color Vision

All colors in the spectrum can be produced by combining red, green, and blue. 3 types of cones are each receptive to 1 of the colors.

• Opponent-process theory

Color is coded in opponent pairs, black-white, yellow-blue, green-red.

• Afterimage

Continuation of a visual sensation after removal of the stimulus

• Depth Perception

Our ability to perceive spatial relationships in 3-D space

• Binocular Cues

Cues that rely on the use of both eyes

• Binocular Disparity

Slightly different view of the world that each of our eyes receive

• Monocular Cues

Cues that require only one eye

• Afterimage

Refers to the fact that we perceive depth when we see two parallel lines that seem to converge in an image

• Pinna

Part of the outer ear that protrudes for our heads

• Tympanic Membrane (AKA the eardrum)

Acts as a barrier that catches sound waves and turns them into physical vibrations

• Ossicles

3 tiny bones with the middle ear

• Maaleus (AKA hammer)

transmits and amplifies sound vibrations from the eardrum to the rest of the middle ear

• Incus (AKA anvil)

Transmits and amplifies sound vibrations from the malleus to the staples

• Stapes (AKA stirrup)

Transmit and deliver sound vibrations from the middle ear to the oval window of the inner ear

• The vestibular sense

Part of the inner ear that is involved in balance and movement

• Cochlea

Fluid-filled, snail-shaped structure that contains the sensory receptor cells (hair cells)

• Hair cells

Convert physical sound vibrations and head movements into electrical signals that the brain can understand

• Basilar membrane

Thin strip of tissue within the cochlea

• Temporal theory

Asserts that frequency is coded by the activity level of a sensory neuron

• Place theory

Suggests that different portions of the basilar membrane are sensitive to sounds of different frequencies. Base of basilar membrane responds best to high frequencies and the tip of the basilar membrane responds best to low frequencies.

• Interaural level difference

refers to the fact that a sound coming from the right side of your body is more intense at your right ear than at your left ear because of the attenuation of the sound wave as it passes through your head

• Interaural timing difference

refers to the small difference in the time at which a given sound wave arrives at each ear

• Monaural cues

one eared cues used to localize sound Provide info that helps locate sounds above, below, In front, or behind us.

• Binaural Cues

two eared cues used to localize sound. Provide info on the location of a sound along a horizontal axis relying in patterns of vibration of the eardrum between our 2 ears.

• Deafness

The partial or complete inability to hear

• Congenital Deafness

Being born without the ability to hear

• Conductive Hearing Loss

When sound waves cannot reach your inner ear. Causes include blockage of the ear canal, a hole in the tympanic membrane, problems with the ossicles, or fluid in the space between the eardrum and cochlea.

• Sensorineural Hearing Loss

When soft sounds are hard to hear and louder sounds are muffled or unclear. Caused by many things like aging, head trauma, infections/diseases, medications, noise exposure, tumors, and toxins.

• Meniere's Disease

Results in a degeneration of inner ear structures that can lead to hearing loss, tinnitus, vertigo, and an increase in pressure within the ear. Not treatable with hearing aids, but some may be eligible for cochlear implant treatment.

• Cochlear Implants

Electronic devices that consist of a microphone, a speech processor, and an electrode array. Receives incoming sound info and directly stimulates the auditory nerve to transmit info to the brain.

• The chemical senses

Taste (gustation) and Smell (olfaction) are called chemical senses because both have sensory receptors that respond to molecules in the food we eat or the air we breathe

• Taste (AKA Gustation)

We have at least 6 basic groupings of taste, which are sweet, salty, sour, bitter, Umami, and fatty content

• Umami

A Japanese word that roughly translates to yummy, associated with a taste for monosodium glutamate

• Taste Buds

Formed by groupings of taste receptor cells with hair like extensions that protrude into the central pore of the taste bud. Life cycle of 10 days to 2 weeks, so destroying/burning some won't have long term affects

• Taste Information

Transmitted to the medulla, thalamus, limbic system, and to the gustatory cortex (which is tucked underneath the overlap between the frontal and temporal lobes)

• Smell (AKA Olfaction)

Perceiving odors through the nose or the specific quality of a thing that affects the olfactory nerves

• Olfactory Receptor Cells

Located in a mucous membrane at the top of the nose. Small hair like extensions from these receptors serve as the sits for odor molecules dissolved in the mucus to interact with chemical receptors located on these extensions

• Olfactory Bulb

A bulb like structure at the tip of the frontal love where the olfactory nerves begin. Information is then sent from here to regions of the limbic system and to the primary olfactory cortex, which is near the gustatory cortex.

• Gestalt Psychology

Perceiving motion in rapidly flickering static images

• Figure-ground relationship

Tend to segment our visual world into figure and ground. Figure is the object or person that is the focus of the visual field, while ground is the background.

• Proximity

Things that are close to one another tend to be grouped together

• Similarity

Things that are alike tend to be grouped together

• Continuity

More likely to perceive continuous, smooth flowing lines rather than jagged, broken lines

• Closure

Organize perceptions into complete objects rather than as a series of parts

• Pattern Perception

Our ability to discriminate among different figures and shapes

• Perceptual Hypotheses

Educated guesses that we make while interpreting sensory info