PSYB57H3 Study Guide - Midterm Guide: Functional Magnetic Resonance Imaging, Visual Cortex, Stroop Effect

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PSYB57 Textbook Notes Chapter 1-6
Chapter 1- Introduction
Information theory- information reduces uncertainty in the mind of the receiver. (the amount of information a message conveys is an increasing
function of the number of possible messages from which that particular message could have been selected)- The less likely it is; the more
information it conveys.
-The more information a signal provides; the more time it takes a subject to produce the appropriate response.
Broadbent’s filter model:
oDichotic testing and restriction of channel capacity
Waugh and Norman’s model:
o“short term belongs to the present while long term belongs to the past”
Brown-Peterson task: memory task. Give a set of items to remember and after a number that they have to count in reverse. (now allowing for
rehearsal to happen)
Perceptual cycle- the process by whereby our schemata (expectations of what we are likely to find in the world) guide our exploration of the world
and in turn are shaped by what we find there.
Chapter 2- cognitive neuroscience
Event related potentials- used to measure the time course of the flow of sensory information and response-related processes, the
electrical signals emitted by the brain can be recorded using electrodes placed on the scalp. They are represented by waveforms and are
the electrical signals that occur after the onset of an stimulus.
Positron Emission Tomography (PET) the part of the brain that engages when a task is performed uses more oxygen and in order to
replenish the oxygen there is an increase in blood flow (uses radiation to detect blood flow)
Functional Magnetic Resonance Imaging (fMRI) measures blood flow and it does not depend on radioactive signal. By placing individual
in a magnetic field, it causes the atoms to become aligned and changes in alignment tracts the changes in blood flow.
Magnetoencephalography(MEG) measures the magnetic fields produced by electrical activity in the brain (direct measure of neural
activity).
Chapter 3- perception
Perception: the processing of sensory information in such way that it produces conscious experiences and guides actions in the world.
Visual agnosia: the inability to identify objects visually even though they ca be identified using other senses.
D.B patient: Blind area in the lower visual field. Blind sight: condition in which patients with damage to the primary visual cortex are able to make
accurate judgements about objects presented to their blind area even though they report no conscious experience of the object and believe they
are only guessing.
Encoding: the process of transforming information into one or more forms of representation.
Subliminal perception: it operates when a stimulus has an effect on behaviour even though it has been exposed to rapidly or too low an intensity
for the person to be able to identify it.
-Limen: another word for threshold (below threshold: subliminal)
Stimulus onset asynchrony: the temporal delay between the fist stimulus and a masking stimulus
Priming: the tendency for some initial stimuli to make subsequent responses to related stimuli more likely.
Direct vs. indirect measures: participant’s reports that they have seen a stimulus vs. the effects of an undetected stimulus on a subsequent task.
Dissociation paradigm: an experimental strategy design to show that it is possible to perceive a stimulus in the absence of any conscious
awareness of them. ‘Perception without awareness’
Objective threshold: level at which people detect a target stimulus no more often than would be expected by chance.
subjective threshold: the point at which the participant says the did not perceive the stimulus (might have been presented too quickly or
at a low intensity)
Process dissociation procedure: an experimental technique that requires participants not to respond with items they have observed previously
Implicit perception: the effect on a person’s experience, thought, or action of an object in the current stimulus environment in the absence of, or
independent of conscious perception.
-Percept: visual experience of sensory information
Theory of ecological optics: the proposition that perception is based on direct contact of the sensory organs with stimulus energy emanating from
the environment and that an important goal of perception is action.
-Ambient optical array: all the visual information that is present at a particular point of view.
-Gradient of texture density: incremental changes in the pattern on a surface which provides information about the slant of the surface.
-Topological breakage: the discontinuity created by the intersection of two textures.
-Scatter-reflection: the degree to which light scatters when reflected from a surface (rough surfaces reflects light more widely than a
smooth surface.
Transformation of optic array: the change of optical information hitting the eye when the observer moves through the environment.
-Optic flow field: the continually changing pattern of information that results from the movement of either objects or the observer through the
environment.
Pattern recognition: the ability to recognize an event as an instance of a particular category of event.
Memory trace: a trace that an experience leaves behind in memory
Hoffding function: the process whereby an experience makes contact with a memory trace, resulting in recognition.
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Template-matching theory: the hypothesis that the process of pattern recognition relies on the use of templates or prototypes
-Prototypical: representative of a pattern or category.
Multiple trace memory model: traces of each individual experience are recorded in memory. No matter how particular kind of event is experience,
a memory trace of the individual event is recorded each time.
-Secondary memory can be activated by means of a probe (a snapshot of information in primary memory that can activate memory traces in
secondary memory).
-Activated memory traces return an echo (made up of contributions from all the activated memory traces)
Feature detection theory: detecting patterns on the basis of their features or properties.
-Pandemonium: a model of pattern recognition of three levels: data (features), cognitive demons (looking to detect a particular pattern), and
decision demon.
Contrast energy is referred to as the relative ease with which a stimulus can be distinguished from the background against which it is displayed.
-Squelching: the tendency of the nervous system to inhibit processing of unclear features (reliability on the expense of efficiency)
Context effect: the influence of proximate stimuli and the situation on the perceptual experience of a stimulus.
-Moon illusion: the tendency for the moon to appear different in size depending on where it is in the sky.
Apparent distance theory: an explanation for the moon illusion. It posits that the moon on the horizon appears larger because distance cues lead
the observer to perceive it as being farther away than the zenith moon.
Empirical theory of color vision: colour perception involves not only the processing of wavelengths of light but also the influence of prior
experiences with the way different surrounding objects and different lightning conditions affect the appearance of the object.
McGurk effect: the auditory experience of the syllable ‘da’ when seeing a mouth silently saying ‘ga’ white at the same time hearing a voice say ‘ba’.
Grand illusion of perception: The illusion that what we see in our visual field is a clear and detailed picture of the world.
Feature integration theory: before we can attend to objects in the world we must extract the features that constitute them – This is achieved
through: Preattentive processing: the unconscious extraction of features that must take place before we can perceive an object.
-Feature binding: the combining of visual features to form a whole object, a process that takes place when attention is directed at a
particular location.
Constrains of the visual system high fidelity percept of the world is not possible because:
1. Visual information is degraded as it moves through the visual organs to the brain
2. Information from all areas of viewed space is not equally represented in the brain
Perceptual completion: the incorrect impression that a stimulus occupies a section of the visual scene when in fact it occupies only the surrounding
region (of the blind spot in the retina- no photoreceptors)
Organizational principles: the rules or laws that govern who whole objects or events are perceived from a collection of individual elements
-Principle of experience: visual elements are grouped together based on prior experience and knowledge of the observer
-Figure-ground segmentation: perceptual organization of a scene such that one element becomes the foreground and the other element
becomes the background.
oDenotivity: the degree to which an object is meaningful and familiar to an individual observer.
Limitations of gestalt perception:
-Ceteris paribus: other things being equal.
-Gestaltist’s error: the assumption that whole object will always dominate over the elements of an image
Chapter 4: ATTENTION
DICHOTIC LISTENING: participants exposed to 2 verbal messages simultaneously, required to answer questions from only 1 of the messages, if they
knew in advance which voice contained the right message, they were good at selective attention - attending to relevant info & ignoring irrelevant
info.
-Broadbent Cocktail Party Phenomenon: able to attend to one convo in a room with many convos going on
-Shadowing task: participants wear headphones, given 2 messages, 1 in each ear. Participants shadow 1 of 2 messages repeating it as they
hear it
Early info processing theories suggest people filter out info they do not wish to attend to thus 1 stage of info processing can involve a
kind of filter that admits some messages and blocks others
-Selective looking: occurs when people exposed to 2 events simultaneously but attend to only 1 e.g. watching b ball and hockey on the
same TV screen, and being able to tune to the b ball without getting distracted by the hockey
Early selection view of attention: attention can prevent early perceptual processing of irrelevant distractors
Late selection view of attention: both relevant and irrelevant stimuli perceived but participants actively ignore the irrelevant stimuli to
focus on the relevant ones
ATTENTIONAL BLINK
Attentional blink (AB):
Failure to notice second of two stimuli presented within 550 milliseconds of each other
Measured using rapid serial visual presentation (RSVP) - presentation of series of stimuli in quick succession
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Detection may improve when accompanied by task-irrelevant mental activity (Olivers & Nieuwenhuis, 2005) thus allocating some
attention to secondary task can improve performance in the primary task
SIMON EFFECT Reaction times are usually faster and more accurate when the stimulus occurs in the same relative location as the response even if
the stimulus-location is irrelevant to the task
SPATIAL CUEING when attention is directed to a particular location in space, items that are located within that space are
processed more efficiently
STROOP EFFECT
Stroop task: A naming task in which colour names are printed in colours other than the colours they name.
Congruent RED
Incongruent RED
Longer reaction times to name the ink colour of incongruent colour words than congruent words
Illustrates controlled versus automatic processes
Controlled processes are activities we must attend to if we’re going to execute them properly, ie., colour naming - also called top down, goal
directed, or voluntary
Automatic processes do not require attention to run smoothly, ie., reading - also described as bottom up, stimulus driven, or involuntary
-Dorsolateral Prefrontal Cortex - area of brain that may exert top down bias favouring selection of task-relevant info
-ACC (anterior cingulate cortex) - area of brain detecting conflicting response tendencies of the sort that stroop task elicits
Attention Capture: diversion of attention by stimulus so powerful that it makes us notice even when attention is focused on something else e.g.
someone calling your name
Inattentional blindness: reverse of attention capture, failure to notice events we might be expected to notice e.g. gorilla videos
Mack and Rock Paradigm: hypothesized that if priming effect observed for word which participants inattentionally blind to, that it would indicate
that the unseen word was registered and encoded below level of conscious awareness
Found that participants who had been shown the word chart and claimed not to have seen it much more likely to create that word when given just
cha
Ecologically valid: generalizable to conditions in the real word
Paradigm shows that many unattended stimuli outside persons immediate focus of attention not consciously experienced but could be if focus
changed so it was directed to relevant spatial locations
Paradigm also showed that faces can be special
Flanker test: experiment where participants may be influenced by irrelevant stimulus beside target. Participants had to search computer screen for
name of famous person and indicate whether that person was show business personality, or politician, name could appear in any location on
screen either by itself or within list of letter strings. In addition, on periphery of screen was picture of either person whose name was being sought
(congruent condition) or person from opposite category (incongruent condition). Participants told to ignore face and when they found name to
press a key for politician or celebrity.
Took longer to ID name correctly as number of alternatives on name list increased
Incongruent conditions took longer than congruent ones - indicates faces not ignored but interfered with reaction time
Also performed with fruits and musical instruments but found that faces continued to distract participants but fruits and musical instruments did
not thus attention to faces may be mandatory
Domain specific modules: hypothesis that parts of brain may be specialized for particular tasks like recognizing faces
DUAL-TASK INTERFERENCE: THE PERCEPTUAL REFRACTORY PERIOD (PRP) PARADIGM
Can do more than one simple task at a time but gets more complex as they begin to interfere with each other
Dual tasks and Limits of Attention
Capacity model: hypothesis that attention can support only a limited amount of attentional activity
Structural limits: attentional tasks interfere with one another to extent they involve similar activities e.g. imagining a sentence and then
categorizing each word as a noun or not is difficult to do at the same time
Interference between tasks more likely to occur if they draw on the same processing resources (e.g. 2 verbal tasks)
Some theories require a central processor - can only pay attention to 1 thing at a time because central processor only can handle one task, if
another added, processor must switch from 1 task to another
Central bottleneck: hypothesis that there is only 1 path along which info travels, so most it can handle at one time is the info relevant to 1 task
Divided Attention: ability to attend to more than 1 thing at a time
Hirst and Neisser study: trained participants to read short stories while copying dictated words and were then given comprehension tests
regarding what they had read - difficult at first but picked it up in 6 weeks. However, they did not pick up info about words being dictated to them
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