What is sensation?
sensation is detecting physical energy from the environment and converting it into neural signals
o Occurs when specialized receptors in the body are activated allowing various forms of outside stimuli to become neural signals in the brain
o Process by which information from outside world enters brain § Information enters through sensory receptors ( tongue, ear, etc.)
Convert different stimuli into neural activity Consciously or unconsciously
What is Transduction?
Transduction is converting outside stimuli into neural activity.
What is perception?
When we select, organize, and interpret our sensations, the process is called perception. Perception occurs when we give meaning to our sensations, interpreting them.
What are the five senses of transduction?
- Taste (gustation): food molecules chemical signals coming in
- Vision: light (photons)
- Hearing ( audition): sound waves
- Touch (somatosentaion): pressure and temperature
- Smell (olfaction): molecules in the air
Who was Ernest Weber?
Ernest Weber (1795-1878)
o Just noticeable differences- smallest difference between two stimuli that is detectable 50% of the time; whatever the difference might be, it is always a constant
o Ex: lifting a 55lb weight and a 50lb weight and half the time you say there is a difference
What is absolute threshold?
Absolute Threshold: Minimum stimulation needed to detect a particular stimulus 50% of the time.
What is the difference threshold?
Difference Threshold: Minimum difference between two stimuli required for detection 50% of the time, also called just noticeable difference (JND).
What is Weber law?
Weber’s law in humans, difference thresholds (experienced as a jnd) increase in proportion to the size of the stimulus
Two stimuli must differ by a constant minimum percentage to be perceived as different
What are Sublimal Threshold?
Subliminal stimuli are those just strong enough for our sensory receptors to pick them up, but not strong enough for us to be able to detect them
What is habituation?
Habituation is tendency of the brain to stop tending to constant, unchanging information; air conditioning; at the neural level
What is the priming effect?
Priming effect reveals that we can process some information from stimuli too weak to recognize, No powerful enduring effects but really subtle
What are microsacchades?
Microsacchades constant movement of the eyes; tiny little vibrations that people do not notice consciously; prevents sensory adaption to visual stimuli
What is sensory adaptation?
Sensory adaption is the tendency for the sensory receptors to be less responsive to stimulus unchanged; don’t send the signals to the brain
What is transduction?
Transduction is the transformation of stimulus energy into neural impulses.
What is photo transduction?
Photo transduction Conversion of light energy into neural impulses that brain can understand.
Color is determined by wavelength. What is a wavelength?
Wavelength is determined by the length of the wave, distance between wave peeks
The brightness of a color is determined by amplitude and intensity of a wavelenght. What is amplitude and intensity?
- Amplitude is determined by the height of the wave, how high or low the wave actually is
- Intensity is the amount of energy in a wave; determined by amplitude; related to perceived brightness
What determines saturation?
Determined by whether or how much there is a mixture of wavelengths.
What are the parts of the eye?
The parts of the eye are the cornea, iris, lens, and the retina.
What is the cornea?
Cornea Transparent tissue where light enters the eye.
What is the iris?
The Iris is the muscle that expands and contracts to change the size of the pupil for light.
What are the lens?
The lens focuses the light rays on the retina ( through visual accommodation a process by which the eye’s lens changes the shape to help focus near or far objects on the retia)
What is the retina?
Retina Light sensitive inner surface of the eye containing photoreceptor rods and cones plus layers of other neurons (bipolar and ganglion cells that process visual information)
What are rods and cons?
- 6 million
- Low sensitivity to dim light
- Located in fovea
- Color and detail sensitive
- 120 million
- Responsible for peripheral vision
- Allow eyes to adapt to low levels of light; high sensitivity to dim lighting
- Not color or detail sensitive
What are bipolar cells?
Bipolar cells receive information from photoreceptors and transmit them to the ganglion cells which form the optic nerve.
What are optic nerve cells?
Optic nerve: carries neural impulses from the eye to the brain
What is a blind spot?
Blind spot is the point where optic nerve leaves the eye, because there are no receptor cells located here, it creates a blind spot
What is a Fovea?
Fovea is the central point in the retina, around which the eye’s cones cluster.
Describe the process of visual processing?
At the optic chiasm, information crosses and left eye information is sent to right brain and vice versa. Optic nerves connect to the thalamus in the middle of the brain and the thalamus (switchboard of the brain directing sensory information with the exception of smell) to the visual cortex.
What is trichromatic theory?
Trichromatic theory: theory of color vision that proposes three types of cones: red, blue, and green. Light of any color can be matched by the additive mixture of these three primary colors, Most known facts about color blindness are explained well through this theory. Trichromatic is good with explaining how cones work.