Chapter 6 Flashcards
Face blindness
Prosopagnosia
What is sensation?
The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
What is perception?
The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
Bottom-up processing
Analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information
Top-down processing
Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations
Transduction
Conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brain can interpret
Absolute threshold
The minimum stimulation needed to detect a particular stimulus 50% of the time
Signal detection theory
A theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and the detection depends partly on a person’s experience, expectations, motivation, and alertness.
All of our senses do what?
1) Receive sensory stimulation, often using specialized receptor cells
2) Transform that stimulation into neural impulses
3) Deliver the neural information to our brain
What is the rough distinction between sensation and perception?
Sensation is the bottom-up process by which the physical sensory system receives and represents stimuli. Perception is the top-down mental process of organizing and interpreting sensory input
Subliminal
Below one’s absolute threshold for conscious awareness
Priming
The activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response
Difference threshold
The minimum difference between two stimuli required for detection 50% of the time. We experience the difference threshold as a just noticeable difference (or jnd)
Weber’s law
The principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)
Using sound as your example, illustrate the distinctions among these concepts: absolute thresholds, subliminal stimulation, and difference thresholds
Absolute threshold is the minimum stimulation needed to detect a particular sound (such as an approaching bike on the sidewalk behind us) 50% of the time. Subliminal stimulation happens when, without our awareness, our sensory system processes that sound (when it is below our absolute threshold). A difference threshold is the minimum difference needed to distinguish between two sounds
Sensory adaptation
Diminished sensitivity as a consequence of constant stimulation
Perceptual set
A mental predisposition to perceive one thing and not another
When we are constantly exposed to stimulus that does not change, we become less aware of it because our nerve cells fire less frequently
Sensory adaptation
Sensory adaptation allows us to focus on?
Changing stimuli
Context creates an expectation that _________ influences our perception
Top-down (information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations)
This curious phenomenon suggests that the brain can work backward in time to allow a later stimulus to determine how we perceive an earlier one
Context
Our motives also direct our?
Perception of ambiguous images
In the context of sensation and perception, what does it mean to say that “believing is seeing”?
Because of perceptual set, our experiences, assumptions, and expectations sculpt our views of reality
Does perceptual set involve bottom up or top down processing? Why?
Top-down drawing on our experiences, assumptions, and expectations
The distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission
Wavelength
The dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth
Hue
The amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the waves amplitude
Intensity
Retina
The light sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information
The process by which the eye’s lens changes shape to focus near or far objects on the retina
Accommodation
Bees can see?
Ultraviolet light
Light enters the eye through the 1)_______, which protects the eye and bends light to provide focus. The light then passes through the 2) ______, a small adjustable opening surrounded by the 3) _______, a colored muscle that controls the size of the pupil by dilating or constricting in response to light intensity and even to inner emotions. Behind the 4) _____ is a transparent 5) ______ that focuses incoming light rays into an image on the 6) ______, a multilayered tissue on the eyeball’s sensitive inner surface
1) Cornea
2) Pupil
3) Iris
4) Pupil
5) Lens
6) Retina
The lens focuses the rays by?
Changing its curvature and thickness, in a process called accommodation
Rods are
Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don’t respond
Cones are?
Retinal receptor cells that are concentrated near the center of the retina & that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations
Optic nerve
The nerve that carries neural impulses from the eye to the brain
Blind spot
The point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there
Fovea
The central focal point in the retina, around which the eye’s cones cluster
If you could follow a single light energy particle to the back of your eye, you would first make your way through the retina’s outer layer of cells to its buried receptor cells, the
1) ____ and _____. There you would see light energy trigger chemical changes that would spark neural signals, activating nearby 2) ________. These cells in turn would activate the neighboring 3) _________, whose axons twine together like the strands of a rope to form the 4) ________.
1) Rods and cones
2) Bipolar cells
3) Ganglion cells
4) Optic nerve
Rods and cones differ in where they are found and in what they do. Describe the cones
The cones cluster in and around the fovea. Many have their own hotline to the brain, which devotes a large area to input from the fovea. These direct connections preserve the cone’s precise information, making them better able to detect fine details.
- Enables you to perceive color
- In dim light they become ineffectual so you see no colors
Rods and cones differ in where they are found and in what they do. Describe the rods.
The rods do not have a hotline like the cones do; they share bipolar cells with other rods, sending combined messages. Rods predominate in outer regions of our retina.
- Enable black and white vision
- Sensitive to dim light
Rods and cones each provide a special sensitivity
Rods to faint light and cones to detail and color
Pathway from the eyes to the visual cortex
Ganglion axons forming the optic nerve run to the thalamus, where they synapse with neurons that run to the visual cortex
