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Chapter 4

Chapter 4 Notes.docx

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Department
Psychology
Course Code
PSYC 221
Professor
Yaroslav Konar

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Page 82-112, 30 pages Page 1 of9 Chapter 4: Attention • Attention: The ability to focus on specific stimuli or locations. • Selective Attention: The focusing of attention on one specific location, object, or message. • Overt Attention: Shifting attention by moving the eyes, as the movements provide observable signals of how attention is changing over time. • Covert Attention: Attention is shifted without eye movement • Divided Attention: Attending to two or more things at once; can be overt, covert, or a combination SELECTIVE ATTENTION • “The taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. It implies withdrawal from some things in order to deal effectively with others,” according to William James. • Selective attention not only highlights whatever is being attended, but keeps us from perceiving whatever is not being attended to. This can occur with any of our senses – vision, hearing, smell, touch, taste. • Attention is a relatively distributed, rather than modular, process occurring over several brain areas Selective Attention as Filtering • Dichotic Listening (Cherry, 1953): Different messages are presented to the two ears. Participants are instructed to pay attention to the message presented to one ear, repeating it out loud by shadowing [to confirm their attention], and ignore the message presented to the other ear. • The content of the unattended message is not processed or remembered, although the voice gender could be identified. • Early Selection Model (Broadbent): Sensory memory holds all incoming information for a fraction of a second. o The filter then identifies the attended message based on physical characteristics (tone, pitch, speed, accent), and lets only this message pass through while all others are filtered out – acts like bottleneck o The detector processes information to determine higher-level characteristics such as meaning. o Short-term memory receives the output and holds the information for 10-15 seconds; may transfer it into long- term memory • Cocktail Party Effect (Moray, 1959): Disproves Broadbent’s model since certain information in the unattended message can still be accessible to the consciousness. This information includes: the individual’s name, distinctive or emotional messages such as “Fire!”, taboo words, and sexually explcit information. • “Dear Aunt Jane” experiment with dichotic shadowing, where the attended ear received “Dear 7 Jane” and the unattended “9 Aunt 6”. However, rather than reporting “Dear 7 Jane”, participants report hearing “Dear Aunt Jane”. This means the participant’s attention had jumped from one ear to the other, taking meaning of the words into account with top-down processing. • Attenuation Theory of Attention (Treisman 1964): Attenuator analyzes incoming message not only in terms of its physical characteristics, but its language (grouping into syllables or words) and its meaning. This analysis only proceeds so far as is necessary to identify the attended message. Page 82-112, 30 pages Page 2 of9 • Once identified, both are let through the attenuator – but the attended at full strength and the unattended at low levels (still present but weak due to “leaky filter”). • The message is analyzed by the dictionary unit, which contains stored words with differing thresholds of activation. Words which are common or especially important, such as one’s name, have a low threshold – and can be detected even if obscured by other stimuli. Uncommon words have higher thresholds and take a stronger signal to be activated, such as nonsense word “rutabaga”. • Signal Detection Theory: A signal is a relevant stimulus that we detect after it passes the threshold of activation. E.g. Brightness can be perceived after passed threshold for the number of photons activating photoreceptors. In the attenuation theory above, different signals have different thresholds. • These are examples of early selection theories, proposing a filter at an early stage in the flow of information. • Late selection models propose that the incoming information is processed to the level of meaning before the message to be processed is selected. Based on ambiguous sentences such as “They were throwing stones at the bank” heard by the attended ear being influenced by biasing words presented to the unattended ear – the unattended biasing word must have been processed to the level of meaning. • The “early-late” controversy is not yet solved Composite Face Effect • Task is to look at the TOP halves of two sets of faces while ignoring the bottom halves, and to determine whether the tops are the same or different. The tops and bottoms may either be aligned or misaligned. • Showed that participants were unable to ignore the bottom half of the face, with accuracy for whether the tops are same or different being around 60% while misaligned was close to 90%. • Similarly, aligned condition had lower reaction time as participants had to actively try to ignore the bottom half of the face, at 800ms versus 600ms for misaligned. Supports idea that we process faces holistically (Gestalt). Cognitive Resources, Cognitive Load, and Task-Irrelevant Stimuli • Cognitive Resources: Cognitive capacity to be used for carrying out various cognitive tasks. Cognitive load is the amount of a person’s cognitive resources needed to carry out a particular task. • Low-load tasks are easy and well-practiced, using a small amount of cognitive resources, while high- load tasks are difficult and require more. • The amount of cognitive resources that is used up as a person is carrying out a primary task determines how much remains, and therefore their ability to attend to another, task-irrelevant stimuli. Flanker Compatibility Task • Flanker Compatibility Task (Eriksen & Eriksen, 1974): Task is to selectively attend to the target in the center position, and to press the “z” key if either A or B are presented in the center and the “m” key if either C or D is in the center. They are told to ignore the “flanker” stimuli on either side of the central letter which are task-irrelevant – this may be A, B, C, D, or X. Page 82-112, 30 pages Page 3 of 9 • Compatible flankers are associated with the same response as the target, e.g. B is compatible to A because “z” key is the response for both. Incompatible flankers are associated with a different response, e.g. C requires pressing “m”. X is a neutral flanker since it is not associated with any response. • The target activity of pushing a key is easy and wouldn’t use all of a person’s cognitive resources, so the flanker stimuli should be processed even if unintended. Indeed, this results in slower response time with incompatible flankers than compatible or neutral flankers – the incompatible stimulus and the response it would elicit compete with the response needed for the target stimulus. st • In original experiment, 5 conditions: 1 with noise same as target had fastest reaction time, followed by 2 noise with a compatible response. Then, conditions 5 (heterogenous noise that looks distinct from H) and 4 (heterogenous noise that looks similar to H). The longest response time was noise with incompatible response in condition 3. Increased Load Flanker Task • The target stimulus “X” appears somewhere in a ring of 6 stimuli, and the flanker stimulus “N” is presented off to the side. The target is told to press a different key for X and N; sometimes N is the target and X is the flanker – in both cases, since they are associated with different responses, they are incompatible. • Sometimes the flanker presented is compatible: target is X and flanker is also X • When “X” is embedded in a circle of “O”s, the task of responding to X is low-load. When “X” is embedded in other letters that are more linear and similar, the task is high-load. • The incompatible flanker causes a slower response in the low-load condition (compared to the compatible low- load condition), but has no effect in the high-load condition (compared to the compatible high- load condition). • Because cognitive resources are available in low-load, the incompatible flanker intrudes to cause slower responding; in high- load, no cognitive resources are available for the incompatible flankers to affect response. • Thus the ability to ignore task- irrelevant stimuli is a function of both the load of the target task, and of how powerful the task-irrelevant stimulus is. The Strop Effect • Strop Effect: Difficult to name each stimulus by the colour of its ink instead of its meaning/content (“White” printed in purple ink). Participants have automatized the process of reading, so the color names of the words are always processed very quickly. On the other hand, identifying colors is not a task that participants have to report on very often and, because it is not automatized, it is slower. The fast and automatic processing of the color name of the word interferes with the desired reporting of the ink color. • This allows researchers to test the behind-the-scenes properties of automatized behaviors by noting their influence on more easily measured behaviors. Page 82-112, 30 pages Page 4 of9 • On each trial you are shown a word (RED, GREEN, or BLUE) that was printed in either red, green, or blue font color. Your task was to classify, as quickly as possible, the font color, regardless of the word name. • The independent variable in this experiment was whether the word name and font color were the same or different. The dependent variable was the response time between the appearance of the stimulus and your response. • Word and Font Color Mean RT (ms) Same 648.542 Different 826.375  much slower due to conflict DIVIDED ATTENTION Divided Attention with Practice: Automatic Processing • Schneider & Shiffrin (1977): Divided attention to simultaneously hold memory info about a target stimulus, and pay attention to a series of “distractor” stimuli to determine if the target is somewhere in their midst. • First shown a memory set with target stimuli, such as “3”. Then rapid presentation of test frames that contain distractors, which may or may not contain the “3” from the memory set. • Consistent mapping condition where the targets and distractors were from different categories, with target as a number and distractor as a letter. Even if the memory set target changes from trial to trial, this distinction is clear. • At first, participants must repeat the target items in each memory set to remember them. However, after 600 trials the task became automatic and reached 90% accuracy – attention could be divided successfully to deal with the target and test items simultaneously • Automatic Processing: Processing that occurs without intention, and at a low cost to cognitive resources. These include everyday actions such as walking, driving, or typing. Divided Attention with Harder Tasks: Controlled Processing • Now, varied mapping condition with rules that change from trial to trial since the targets in the memory set and the distractors are both letters. This means a target on one trial can be a distractor on the next, and vice versa (target P on trial 1 is a distractor on trial 2, while target T on trial 2 was distractor on trial 1). • Performance on the consistent mapping condition reaches 90% accuracy when the test frame duration is only 80s, while for varied mapping condition performance needs 400ms presentation for 90% accuracy. • Controlled Processing: Automaticity is never reached, participants must pay close attention at all times, searching for the target among distractors in a much more focused and controlled way. Distractions while Driving Page 82-112, 30 pages Page 5 of 9 • There is a proven connection between cellphone use and traffic accidents. In a laboratory experiment, participants did a simulated driving task where they had to apply brakes as quickly as possible to a red light. • Participants who talked on a cellphone in this task missed 2x as many red lights, and had 100ms slower reaction time in applying the brakes. This occurred regardless of whether the cellphone was handheld or hands-free. • Talking on the cellphone uses cognitive resources needed for driving, decreasing attention and response • Other distracting elements include GPS systems and menu screens, food, reading email, makeup, etc. ATTENTION & VISUAL PERCEPTION Inattentional Blindness • Inattentional Blindness: Failure to notice an obvious unexpected object in the environment because our attention is focused on something else – bottom-up since we do not notice a stimulus • Mack & Rock (1998): Task to indicate which arm of the cross was longer, the horizontal or vertical. Then, on one trial, a small test object in the field of vision was added to the display. In a subsequent recognition test, the subject is told to pick out the object that was presented – unable to because paying attention to the cross had made them “blind” to the unattended test object. • Simons (1999): Film with two teams of basketball players. Observer told to count the number of passes by the white team, and
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