Chapter 2 study guide notes- Response Performance Measures Stimulus Processing

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2 Aug 2010
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Response Performance Measures Stimulus Processing
-Wundt established first laboratory in psych in 1874
-also pioneered many methods for studying how the min d works by examining how people respond on
psychological tasks
-the typical goal of response performance is to quantify how a perceptual or cognitive process responds to a
specific stimulus
-benefit: using response performance as a methodology makes it relatively simple to study cognition and
perception
-researchers infer how a stimulus is processed from how a person responds to it
-quantified in three ways
1. a researcher can measure reaction time (a quantification of performance behaviours that measures the
speed of a response)
-the more processing a stimulus requires, the longer the reaction time that stimulus will be
2. measure response accuracy (how well a stimulus was perceived)
-experiment ! focus on one side of the screen, while the other screen changes and see if the person
can tell whether its the same or different
-if the accuracy of responses is greater for stimuli presented on the side of attention, then attention is
improving the perception of the stimulus
3. measure response performance by stimulus judgments, regarding the different performance with which
they are presented
Body and Brain Activity can be Directly Measured
-activity of body and brain can be measured in different ways
-certain emotional states influence the body in predictable ways
-being frightened causes muscles to become tense and hearts beat faster
-other bodily systems are influenced by mood and mental states
-blood pressure, blood temperatures, rate of perspiration, pupil size, breathing rates
-all are examples of psychophysiological assessment (researchers examine how changes in bodily functions are
associated with behaviour or mental state)
-use of polygraphs allows one to assess these bodily states, under the assumption that people who are
lying experience arousal and are more likely to show physical signs of stress
-correspondence between bodily response and mental state is not perfect
-stressful events can lead to increased heart rate or reduced heart rate
Electrophysiology
-a method of data collection that measures electrical activity in the brain to see how it is related to
cognitive and perceptual tasks
-electroencephalogram (EEG) is the device that measures brain activity by recording overall brain activity
-useful because different behavioural states produce predictable EEG patterns
-shows specific and consistent patterns as people fall asleep and reveals that the brain is very active even
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when the body is at rest, especially during dreams
-at specific cognitive states, the EEG is limited because the recordings reflect all brain activity and
therefore are too noisy to isolate specific responses to particular stimuli
-a more powerful method of how brain activity changes in response to a specific stimuli involves conducting
many trials and averaging across the trials, also known as event-related potential (ERP)
-able to observe patterns associated with specific events
-the real advantage of the EEG and the ERP is not that they provide information about where in the brain an
electrical event comes from, but that they determine exactly when it happens
-provide maps of approximate origins of various electrical signals and give insight into how the brain
processes information on the basis of which regions are activated and when
-electrophysiological measures can be used with other methods to assess complex behaviours
-ie. Drinking and driving
-measured EEGs and ERPs of alcoholics show that their brain responses appear to be muted overall
-many aspects of alcoholism have strong genetic component
-children of alcoholics need to consume much greater quantities of alcohol than most people in order
for them to feel it
Brain Imaging
-electrical activity of the brain is associated with changes in the flow of blood as it carries oxygen and
nutrients to the active brain regions
-brain imaging methods measure such changes in the flow and keeps track of these changes
-researchers can monitor which brain areas are active during a study
-imaging is a powerful tool for uncovering where different systems reside in the brain and the manner in
which different brain areas interact in order to process information
-certain brain regions become active whenever people look at pictures of faces, whereas other brain
regions are active when people try to understand what other people are thinking
-alcohol leads to a one-third reduction in activity in areas of the brain concerned with vision ! may
impair drivers by directly affecting their sight
-positron emission tomography (PET) is a computer-aided reconstruction of the brain’s metabolic activity
through the use of a relatively harmless radioactive substance injected into the bloodstream
-developed in the late 1980s
-patient lies in a special scanner that detects the radiation and a 3-D map of the density of radioactivity
within the participant’s brain is produced
-map is useful because as the brain performs a mental task, blood flow increase to the most active
regions, leading to more emitted radiation
-amount of radioactivity emitted by a brain region roughly corresponds to the amount of electrical activity
in the local neurons
-however, since the brain is extremely metabolically active all of the time, scans must be made while the
participant performs another, closely related task (ie. Looking at pictures of faces with neutral expressions)
-and by subtracting one image from another, experimenters obtain a difference image of which brain
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