Content 6A: Sensing the Environment Flashcards
Sensory processing; Vision; Hearing; Other senses; Perception
Aphasia
disorder that involves language. Aphasia is a communication disorder that causes problems with language, like speaking, listening reading, and writing.
Language and the brain. How does the brain speak and understand the language?
How your brain speaks and understands language. • 90% of people, language is in left hemisphere (both right and left handed people!). Whatever is dominant, 2 main areas are Broca’s area (speak/language expression, frontal lobe) and Wernicke’s area (temporal lobe (sound processing), understand)
Broca’s Aphasia
o When Broca’s is damaged, people have trouble producing speech. Broca’s aphasia (also called non-fluent aphasia). Acronym: Broca’s aphasia = Broken speech. Damage to the language production centers of the brain. Produce broken/halted speech. Frontal lobe region damaged. Broca’s aphasia is characterized by apraxia, a disorder of motor planning, which causes problems producing speech.
Fluent/receptive aphasia
Temporal lope damage Wernicke’s aphasia
Wernicke’s Aphasia
Wernicke’s aphasia is characterized by difficulty understanding spoken words and sentences, as well as difficulty producing sentences that make sense. Persons with Wernicke’s aphasia can produce many words and they often speak using grammatically correct sentences with normal rate and prosody. However, often what they say doesn’t make a lot of sense or they pepper their sentences with non-existent or irrelevant words. They may fail to realize that they are using the wrong words or using a non-existent word and often they are not fully aware that what they say doesn’t make sense. “Word Salad” = lacking meaning of produced speech which is normal (prosody)
The area responsible for the comprehension of the speech
Wernicke’s area “Wernicke’s comprehension is crappy” but “ Broca’s speech is broken”.
Global Aphasia
Both Broca’s Aphasia and Wernicke’s aphasia are damaged. Acronym: Globally affects language. Global aphasia is a combination of impaired comprehension and production of speech.
Arcuate fasciculus
o 2 areas (Wernicke’s and Broca’s) are connected by bundle of nerves fibers called the arcuate fasciculus, also found in deaf people who know sign language. Not specific to spoken language, but brain adapts to whatever modality is needed for communication.
Conduction Aphasia
damaged to the arcuate fasciculus. the connection between speaking and listening is broken- They understand what they hear but difficulty repeating back.
Sensation vs Perception
prosopagnosia (face blindness)
sensation: the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.
sensory receptors: sensory nerve endings that respond to stimuli.
perception: the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.
When she looks at a friend, her sensation is normal: Her sensory receptors detect the same information yours would, and her nervous system transmits that information to her brain. Her perception—the processes by which her brain organizes and interprets sensory input—is almost normal.
Under normal circumstances, sensation and perception blend into ………….. .
one continuous process.
Top-down and bottom-up processing
Bottom-up processing
Bottom-up processing starts at your sensory receptors and works up to higher levels of processing.
Top-down processing
constructs perceptions from this sensory input by drawing on your experience and expectations.
As your brain absorbs the information in this figure ———– enables your sensory systems to detect the lines, angles, and colors that form the flower and leaves.
bottom-up processing
LOQ 6-2 What three steps are basic to all our sensory systems?
Our senses:
- receive sensory stimulation, often using specialized receptor cells.
- transform that stimulation into neural impulses.
- deliver the neural information to our brain
Transduction
The process of converting one form of energy into another that our brain can use is called transduction. Transduction is rather like translation—of a physical energy such as light waves into the brain’s electrochemical language.
What is the rough distinction between sensation and perception?
Sensation is the bottom-up process by which your sensory receptors and your nervous system receive and represent stimuli. Perception is the top-down process by which your brain creates meaning by organizing and interpreting what your senses detect
Absolute threshold
the minimum stimulation necessary to detect a particular light, sound, pressure, taste, or odor 50 percent of the time.
To test your absolute threshold for sounds, a hearing specialist would send tones, at varying levels, into each of your ears and record whether you could hear each tone.The test results would show the point where, for any sound frequency, half the time you could detect the sound and half the time you could not. That 50-50 point would define your absolute threshold.
signal detection theory
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 that detection depends partly on a person’s experience, expectations, motivation, and alertness.
Subliminal Stimuli
Stimuli you cannot consciously detect 50 percent of the time are subliminal—below your absolute threshold
One experiment using subliminal stimuli illustrated the deep reality of sexual orientation.
The hidden mind experiment
As people gazed at the center of a screen, a photo of a nude person was flashed on one side and a scrambled version of the photo on the other side.Because the nude images were immediately masked by a colored checkerboard, viewers consciously perceived nothing but flashes of color and so were unable to state on which side the nude had appeared.
To test whether this unseen image had unconsciously attracted their attention, the experimenters then flashed a geometric figure on one side or the other. This, too, was quickly followed by a masking stimulus that interrupts the brain’s processing before conscious perception. When asked to give the figure’s angle, straight men guessed more accurately when it appeared where a nude woman had been a moment earlier. Gay men (and straight women) guessed more accurately when the geometric figure replaced a nude man.
As other experiments confirm, we can evaluate a stimulus even when we are not consciously aware of it—and even when we are unaware of our evaluation
Subliminal sensation in rating of people
Priming
priming: the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response
The Difference Threshold
(JND)
is the minimum stimulus difference a person can detect half the time.
That detectable difference increases with the size of the stimulus.
If we listen to our music at 40 decibels, we might barely detect an added 5 decibels (the jnd). But if we increase the volume to 110 decibels, we probably won’t detect an additional 5-decibel change.
Weber’s Law
For an average person to perceive a difference, two stimuli must differ by a constant minimum percentage (not a constant amount).
The exact percentage varies, depending on the stimulus. Two lights, for example, must differ in intensity by 8 percent. Two objects must differ in weight by 2 percent. 790And two tones must differ in frequency by only 0.3 percent
Using sound as your example, explain how these concepts differ: absolute threshold, subliminal stimulation, and difference threshold.
Absolute threshold is the minimum stimulation needed to detect a particular sound (such as an approaching bike on the sidewalk behind you) 50 percent of the time.
Subliminal stimulation happens when, without your awareness, your sensory system processes a sound that is below your absolute threshold.
A difference threshold is the minimum difference needed to distinguish between two stimuli (such as between the sound of a bike and the sound of a runner coming up behind you) 50 percent of the time.
Sensory Adaptation
Why, then, if we stare at an object without flinching, does it not vanish from sight?
Deminished sensitivity as a consequence of constant stimulation.
Because our eyes are always moving.
Our gaze jumps from one spot to another/ visual fixation
Sensory adaptation
Emotion adaptation
Sensory adaptation even influences our perception of emotions. By creating a 50-50 morphed blend of an angry face and a scared face, researchers showed that our visual system adapts to a static facial expression by becoming less responsive to it (Butler et al., 2008)
Perceptual Set
To see is to believe. As we less fully appreciate, to believe is to see.
Through experience, we come to expect certain results. Those expectations may give us a perceptual set—a set of mental tendencies and assumptions that affects, top-down, what we hear, taste, feel, and see.
