The skin provides information about pressure, pain, and temperature.
The myelinated cells that send information to the spine are sensitive to pressure and movement.
Pain information is sent via two types of neurons, one of which is unmyelinated and responsible for the throbbing sense of chronic pain.
The release ofstance P, a chemical signal similar to a neurotransmitter, is triggered when the pain signal reaches the spine.
The signal goes to the thalamus and the cingulate cortex.
A signal is sent from the brain to the spinal cord, which reduces the sensation of pain.
The limbic system and the somatosensory cortexample can be shown by this information.
The sensation of balance is one of the senses.
The semicircular canals of the inner ear are where this sense is located.
Information about the location and position of the limbs and body parts is transmitted by kelesthesis.
This table can be used to compare and contrast sensory systems.
There are three bones in the middle ear that connect the eardrum to the window.
Our sensory systems need to do more than just detect stimulation.
They need to do more than that.
Our sensory systems are dynamic and can detect changes in stimuli intensity and quality.
Adaption and habituation are two processes used to respond to changing stimuli.
A temporary change in response to environmental stimuli is called adaptation.
Our adaptation to being in darkness is an example of this process.
It is hard to see at first, but our visual system adjusts to the lack of light.
Our sensory systems are affected by different stimuli.
The new standard of stimulation is called the adaptation level.
The swimming pool is an example.
If you enter a 75-degree swimming pool from an air-conditioned room, it will feel warm, as your adaptation level is set for the cold room.
If you are on a hot beach and enter the same pool, it will feel cold, as your adaptation level is set for the heat of the beach.
Habituation is the process by which we become accustomed to aStimulus and notice it less and less over time.
When a small change in the environment causes us to notice it again, it's a sign of dissolution.
When aStimulus is removed and then re-presented, there is also dishabituation.
The noise from an air conditioner is an example of a pair of processes.
When we first enter a room, we may notice a noisy air conditioner, but after a few minutes, we barely notice it.
We notice the noise again when the air conditioner's compressor turns on.
This noticing is not normal.
We can control habituation under certain circumstances.
If someone asks us if the noise of the air conditioner is related to something else, we can force ourselves to leave.
The key to distinguishing habituation from sensory adaptation is the control over our information processing.
You can force yourself to pay attention to the things that are near you.
The term attention refers to the processing of a small portion of the massive amount of information that comes from the senses.
In common terms, attention allows us to focus on one small aspect of our perceptual world, such as a conversation, while constantly beingsailed by massive input to all of our sensory systems.
In order to focus on other information, attention serves as a funnel.
The brain doesn't have the skills to process and pay attention to all of the information presented to it.
The brain can be tricked through illusions due to the fact that the brain must take short cuts and focus on particular information.
A good example of attention in action is when we try to pay attention to one thing while ignoring another.
We try to ignore the people in front of us at a movie theater.
The "cocktail party phenomenon" refers to our ability to follow a single conversation in a room full of conversations.
Our attention can be drawn to another conversation by key stimuli, such as someone saying our names.
Although we are not paying much attention to the other conversations, we are definitely paying attention to the information we are not consciously aware of.
The phenomenon was studied in the laboratory with headphones, by playing different messages in each participant's ears.
The person is told to repeat one of the conversations.
The repetition is referred to as shadow.
The message is largely ignored.
Key words can draw attention to a message.
There are two main types of theories.
The stimuli must enter into attention through a screen or filter.
Donald Broadbent had a proposal.
The idea of a filter at this level has generally been discarded due to the fact that meaningful stimuli, such as our own names, can catch our attention.
The meaning has already been processed so the filter needs to be at a higher level.
When one message is spoken by a woman and the other by a man, it is easy for people to tell the difference.
The attentional resource theories say that we only have a fixed amount of attention and that this can be divided up as needed.
If you are engrossed in this book, you are giving it all of your attention.
Strong stimulation is the only way to get your attention.
All attention is not equal.
A conversation near you is more likely to interfere with your reading than a noise outside.
When trying to focus on more than one task at a time, it is more difficult than watching TV or reading.
The ability to divide attention with age.
We talked about how environmental stimuli affect the receptor systems when we were describing sensory mechanisms.
The section deals with how our mind interprets stimuli.
There are two theories of perception.
The recognition of an object is achieved by breaking it down into its component parts.
It relies on the senses.
The brain's analysis and the raw acknowledgement data are what bottom-up processing is all about.
When the brain labels a particular experience, top-down processing occurs.
Think about the first time a person tasted a lemon.
The firing of the neurons to alert the brain of the presence of some taste in the mouth is a bottom-up process, whereas labeling it "sour" is the top-down process.
The next time a person sees a lemon, they might salivate or wince.
The perception of the lemon is influenced by the expectation of experience.
We need to see depth, size, shape, and motion.
There are various perceptual cues that facilitate depth perception.
Because of the limited ability of the brain to process information, it must make educated guesses based on how the world is normally structured.
The brain can fall prey to illusions and use these cues.
There are two visual perception cues, monocular and binocular.
We only need one eye to see monocular depth cues.
They can be depicted in two-dimensional representations.
The relative size refers to the fact that images that are farther from us have a smaller image on the retina than those that are closer to us.
We expect that object to be closer to us than another.
The idea of texture gradient is related to this idea.
As distance increases, the distribution of objects seem to grow denser.
If we are looking at pebbles in the distance, they appear smooth and uniform, but close up may be jagged and rough.
Interposition is a monocular depth cue that occurs when a near object blocks the view of an object behind it.
Linear perspective is a cue based on the perception that parallel lines draw closer together as they move closer to each other.
Take a picture of yourself standing on a train track.
The rails draw closer together as they move away from you.
The vanishing point is where the rails seem to join.
The two lines become indistinguishable from one another at this point.
The tracks at a point where they differ greatly are assumed to be farther away from objects present near the vanishing point.
The observation that atmospheric dust and moist air obscure objects in the distance more than they do nearby objects is the basis for aerial perspective.
When driving in the fog, a far-off building looks more distant than it really is, but its image quickly becomes clearer and clearer as you approach.
fuzzy images appear to be more distant because of relative clarity.
There is a difference in the apparent movement of objects at different distances when the observer is in motion.
A person on a train can see objects out of a window that appear to be moving in the same direction as the train.
The objects are moving in opposite directions to the train.
Motion parallax is different from other monocular depth cues in that it requires motion and cannot be represented in a two-dimensional image.
Both eyes look at an image.
Each eye sees a different image from a slightly different angle.
Stereopsis is a three-dimensional image of the world.
Your eyes must turn inward slightly in order to focus on near objects.
The eyes must turn inward if they are close to the object.
binocular disparity is caused by the fact that the closer an object is, the less similar the information arriving at each eye will be.
The process can be demonstrated by covering one eye and looking at something directly in front of you.
There are two different views of the object.
The two views appear to be the same if you repeat this procedure with an object across the room.
We can have depth perception with the help of the binocular vision.
The visual cliff was developed to test depth perception.
The glass table was clear on one side and had a checkerboard design on the other.
Most infants refused to do so, which implies that depth perception is innate.
It was not clear how much learning had influenced depth perception because the infant had to be a few months old.
The importance of vision to the survival of the organisms was determined by the testing of other animals.
The visual system needs to perceive and recognize form, that is, size and shape.
The approach to perception is based on a top-down theory.
Most perceptual stimuli can be broken down into figure-ground relationships according to this view.
The figures stand out against the ground.
The famous vase-face example shows that figure and ground can be reversed.
We tend to see objects in their simplest forms when we look at these Gestalt principles.
A feature detector approach is used in a different theory of form recognition.
The Law of Pragnanz reduces an image to its simplest form by suggesting that organisms respond to specific aspects of a particular stimuli.
When driving a car, we use feature detection to anticipate the movement of other cars and pedestrians that demand our attention, helping us to be more aware of the environment.
Another important perceptual process is assent.
We know that aStimulus remains the same size, shape, brightness, weight, and/or volume even though it does not appear.
People who have never seen an airplane on the ground will have a hard time seeing the plane's actual size.
The ability to achieve constancy, which is innate, and the experience, which is learned, both contribute to our development of the various types of constancy.
Motion detection is one of the most complex abilities we have.
We can see motion through two processes.
One records the position of an object as it moves.
The other tracks how we move our heads.
The brain interprets the information with special motion detectors.
The perception of apparent motion is a related issue.
Some examples of apparent movement include blinking lights on a roadside arrow, which give the appearance of movement, a motion picture where still pictures move at a fast enough pace to imply movement, and still light that appears to twinkle in darkness.
Chapter 19 has answers and explanations.
Cats notice slight movements under low lighting conditions with greater ease than humans, but they don't find it easy to distinguish colors.