MCAT Sensation, Perception, and Consciousness Flashcards
(48 cards)
Transduction
When an environmental signal is turned into an electrical signal that’s sent to the brain.
Sensory Adaptation
When the strength in the response to a stimulus decreases with prolonged exposure to the stimulus.
Difference threshold (just noticeable difference)
The minimum threshold to differentiate two between two stimuli 50% of the time.
Weber’s law
As the intensity of the stimulus increases so does the just noticeable difference.
Given by the following equation:
(Difference threshold)/ (original stimulus strength) = K
We can find the difference threshold of one stimulus by using the equation and calculating the constant, K.
Absolute threshold
The threshold needed to detect a stimulus 50% of the time.
Signal detection theory
Used to see how external stimuli effects our judgements and decision making.
- Hit = signal presented, correctly identified
- Miss = signal presented, not identified.
- False alarm = no signal present, signal identified.
- correct rejection = no signal, signal not identified.
Sensory receptors, what are the four types?
Sensory receptors take internal and external stimuli and transduce them to the CNS.
- Mechanoreceptors- respond to mechanical stimuli such as pressure, vibrations, movement.
- Thermoreceptors - receptors that respond to a change in temperature.
- Photoreceptors - responds to light.
- Chemoreceptors - responds to chemicals like taste and smell.
Role of the thalamus
Most sensory information is sent here first and then to the appropriate brain regions.
The exception is olfactory stimuli which is sent to the olfactory bulb and then directly to brain regions.
Perception
Making a meaning of neural signals.
Top- down processing
When someone uses previously encoded information in perception of stimuli.
Perceptual set
When someone focus on certain parts of a stimuli but not others.
Perceptual organization
When someone’s experiences and expectation effect their perception of a stimulus.
People can have different perceptions of a stimulus if they have difference experiences and expectations.
Perceptual constancy
When nothing changes to the stimulus when slight changes are done to it when were observing it.
- Shape constancy
- Size constancy
- Color constancy
- Brightness constancy
Depth perception
When a person sees in 3D from the brain’s interpretation of 2D information from the eyes.
Information of depth perception given by monocular cues and binocular cues.
Describe the following monocular cues:
- Interposition
- Relative size
- Height in plane (relative height)
- Motion parallax (relative motion)
- Linear perspective
Monocular cues are cues from one eye that gives us information about depth perception.
- Interposition - When an object is partially blocked by another object the partially blocked object appears further away.
- Relative size - An object that is further away from another object appears smaller.
- Height in plane - objects lower the plane appears closer to us the objects further in the plane.
- Motion parallax - object that’s closer to us seem to be moving faster than objects further away. Think moving in a car.
- Linear perspective - parallel lines going off in the distance appears to come together.
Describe the binocular cues
Binocular cues are cues on depth given by both eyes.
- Retinal disparity - information about depth caused by the slight difference in the images that falls on both eyes.
- Convergence - The brain interprets the angles created by the eyes when they come close together to view close objects and the increase in the angle as it views objects further away.
Phi phenomenon
When adjacent flashing lights are perceived as moving.
Gestalt principles. Describe each one:
1. Law of subjective contours
- Law of similarity
- Law of continuity
- Law of closure
- Law of proximity
Used to explain how the brain examines stimuli as a whole rather than its hearts.
- Law of subjective contours- we perceive the contours (edges) of an object even when it’s not filled in.
- Law of similarity- we group together objects that are similar.
- Law of continuity - we view stimuli as a continuous path, not broken paths.
- Law of closure- we view the whole object by filling in gaps (think “ closing in those gaps”).
- Law of proximity - we see objects that are close together as groups .
What kind of waves is light?
Electromagnetic waves.
Wavelength determines it’s color (hue).
- Amplitude describes its intensity.
Describe the following parts of the eye:
- The cornea
- The pupil
- The iris
- The sclera
- The lens
- The cornea covers the pupil
- The pupil is the opening of the eye that allows light the pass.
- The iris- determines the dilates or constricts the pupil. It’s colored and determines the color of our eyes.
- The sclera- the white part of the eye.
- The lens- changes shape to change how the image falls onto the retina.
Accommodation
The process of the lens changing shape to change how the image falls onto the retina.
Describe the photoreceptors of the eye
Rods responds to movement and white, black, and grey colors.
Cones has high visual acuity and responds to the other colors.
- Centermost region of cones is the fovea which is the highest visual acuity as it’s packed with cones. The middle of the fovea is the macula.
Describe how visual information is passed among retinal cells?
Photoreceptors sends information to bipolar cells which synapses onto the ganglion cells whose axons come together and form the optic nerve. It goes to the thalamus and then to the visual cortex of the occipital lobe.
- The optic disk is where the optic nerve leaves for the thalamus and blood vessels supply blood to the retina. Because of this there’s a blind spot there.
Describe the visual pathway in the brain
Optic nerve crosses over at the chiasm so that information is processed on the opposite side of the brain from where it was transduced.
Now they’re referred to as tracts which goes to the lateral geniculate nucleus of the thalamus and then to the V1 (primary visual cortex)
