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  1. 1. CHAPTER 3
  2. 2. ATTENTION • Refers to selecting certain stimuli from among many and focusing cognitive resources on those selected. • The selection of some incoming information for further processing in memory.
  3. 3. • Allows us to focus on what is important at the moment and to ignore the rest.
  4. 4. William James (1890) • Described attention as, “the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible trains of thought….Focalization (and) concentration of consciousness are of its essence” (pp.403-404) • When attention fails, we are left scatterbrained and unable to function.
  5. 5. Cognitive research on cell phones as a distraction should inform our public policy debates about whether they should be prohibited while driving in much the same way that alcohol use is prohibited.
  6. 6. Attention deficit/hyperactivity disorder • Is a commonly diagnosed psychiatric disorder that occurs most often in children younger than seven. They are easily distracted and excessively restless and impulsive. • ADHD is diagnosed when inattention, hyperactivity, and impulsivity are frequent and severe, beyond the range of normal behavior in young children.
  7. 7. FILTER THEORIES Address the selective nature of attention. Postulate a bottleneck in the flow of information from initial sensory processing to registration in conscious awareness.
  8. 8. SELECTIVE ATTENTION • Refers to the ability to perceive a particular stimulus of interest while ignoring numerous other stimuli.
  9. 9. DIVIDED ATTENTION • Two or more stimuli share cognitive resources.
  10. 10. • DICHOTIC LISTENING – both ears receive stimuli in synchrony and participants are asked to attend to only one ear or channel. • SHADOWING – the participant repeats aloud the stimuli presented to the attended channel and ignores the stimuli presented in the unattended channel.
  11. 11. EARLY SELECTION • Refers to an attentional filter that operates after sensory processing but prior to meaningful semantic processing. • The model also included a store of conditional probabilities about past events, what today is called long- term memory.
  12. 12. Broadbent (1958) • Proposed a model to account for the findings with the shadowing task.
  13. 13. ATTENUATION • Refers to an attentional filter that lowers the strength of the sensory signal on the unattended channel. • The degree of perceptual analysis received by an item depends only in part on its signal intensity.
  14. 14. LATE SELECTION • Refers to an attentional filter that operates after meaningful semantic processing but prior to response preparation. • All stimuli are recognized but are narrowed to the most pertinent ones during response preparation. • The words are fully perceived, but then the perceiver responds only to the most pertinent item.
  15. 15. • Selective attention may result from filtering of the unattended channel. The filter could occur at an early stage, just after sensory processing, or at a late stage, after semantic processing. A third possibility is that the unattended channel is attenuated rather than filtered entirely.
  16. 16. CAPACITY THEORY • Address the allocation of resources to specific mental processes. • Recognize that one or more bottlenecks exist but add the assumption that mental processes compete for limited resources as well.
  17. 17. KAHNEMAN (1973) • Capacity theory assumes that attention is limited in overall capacity and that our ability to carry out simultaneous tasks depends, in part, on how much capacity the tasks require. Selective attention occurs because shadowing demands most of the capacity, leaving little, if any, for the unattended channel.
  18. 18. MENTAL EFFORT • The capacity approach conceives of attention as mental effort. The more a task requires of a limited pool of available capacity, the more mental effort the person exerts. • Example: try to solve these two arithmetic problems in your head: a. 6 x 6 = ? b. 32 x 12 = ?
  19. 19. • Mental effort increases as the proportion of available attentional capacity increases. One way to measure mental effort is through increases in reaction time to a secondary task that competes for limited attentional capacity with a primary task.
  20. 20. MULTIPLE RESOURCES • Multiple resource theories elaborate Kahneman’s approach. The ability to perform two tasks concurrently depends not just on their respective demands on capacity but also on the specific resources required (e.g., perceptual vs. cognitive).
  21. 21. C.D. WICKENS (1980) • Three dimensions of resources: • Auditory vs. Visual perceptual modalities • Perceptual-Cognitive resources vs. Response resources • Verbal vs. Spatial Processing Codes
  23. 23. • Stroop (1935) devised an ingenious and somewhat diabolical test to study automatic reading. The color terms occur automatically and effortlessly. The color terms are printed in an incompatible color of ink. The task is to say aloud the color of the ink while ignoring the meaning of the word itself. • Errors and delays in responding are the usual result.
  24. 24. AUTOMATIC PROCESSES • Require little, if any, mental effort. Moreover, they occur without intentional control; even when an individual attempts to stop an automatic process from operation, it unfolds anyway, as demonstrated by the Stroop effect. • Operate outside the scope of conscious awareness. • Processes develop automatically either through genetic programming or as the result of extensive practice. • Preattentive
  25. 25. AUTOMATIC PROCESSES • Posner and Snyder categorized a process as automatic if it met three criteria: • Occurs unintentionally • Occurs unconciously • Operates without depleting attentional resources
  26. 26. CONTROLLED PROCESSES • Intentional, conscious, and demanding of attention • They demand extensive mental effort, they require intentional control to operate, and they enter conscious awareness.
  28. 28. NEURAL BASIS OF SELECTION • Neurons in the occipital cortex act as feature detectors tuned to respond maximally to highly specific visual features, such as a line at a particular orientation.
  29. 29. • The line must stimulate a specific area in the retina of the eye, which defines the receptive field for the neuron in question. • A group of cells in the retina—the receptive field—all map onto a specific neuron in the cortex that is “looking for” the feature to which it is tuned.
  30. 30. • The control of these changes in receptive fields lies in the thalamus, a structure deep in the midbrain that serves as a crossroad for an extremely large number of sensory pathways.
  31. 31. • Positron emission tomography (PET) scans with humans have revealed increased blood flow— implying increased neural activity—in a portion of the thalamus called the pulvinar thalamic nucleus when observers receive instructions to ignore an irrelevant but clearly visible stimulus.
  32. 32. SPATIAL NEGLECT • This disorder is characterized by a failure to attend to all areas of the visual field. Individuals with damage to the right hemisphere will neglect objects or events occurring in the left visual field.
  33. 33. EXECUTIVE ATTENTION • Refers to a supervisory attentional system that inhibits inappropriate mental representations or responses and activates appropriate ones. • It is important in planning, decision making, and other complex cognitive tasks.
  34. 34. NORMAN and SHALLICE (1986) • Executive Attention is always needed when: • Planning or making decisions • Correcting errors • The required response is novel or not well-learned • Conditions are cognitively demanding or dangerous • An automatic response must be inhibited and overcome.
  35. 35. • When participants perform the Stroop task in conditions that permit PET scans to be taken, a region in the frontal lobe shows strong activation. The anterior cingulate gyrus in the frontal lobe acts as a supervisory attentional system, inhibiting the automatic response and selecting the correct response.
  36. 36. • The disordered perception and thought of schizophrenia appears to be in part related to a breakdown in the normal processes of selective attention. This possibly stems from a disorder in the inhibitory capacities of the prefrontal cortex.
  37. 37. FEATURE INTEGRATION THEORY • Posits that automatic preattentive processing of features must be followed by controlled attentional processing to bind the features into a whole object.
  38. 38. TREISMAN and GELADE (1980) • Required observers to detect a target that differed from distractor items of one dimension, such as color. • Predicted that the number of distractor items should be irrelevant to speed of detection if the observer could automatically recognize all stimulus features in parallel.
  39. 39. POP-OUT SEARCH • The target popped out at the observer.
  40. 40. CONJUNCTIVE SEARCH • The more distractors, the longer it took to find the target.
  41. 41. BINDING PROBLEM • Refers to how the features that are distributed in multiple brain regions are integrated to result in the perception of a single object. • Attention may be what binds the features together prior to conscious perception.
  42. 42. INATTENTIONAL BLINDNESS • A superthreshold stimulus that is directly fixated for 200 milliseconds, a long leisurely glance when attention is (as usual) locked onto the fixation point, is simply not seen. • Provides a compelling, but disturbing, demonstration that attention is necessary for binding together features. • Without attention and the binding that it supports, perception fails.
  43. 43. ATTENTIONAL BLINK • The interval of time after the target is presented when other stimuli in the series are not perceived. • This interval seems to be a refractory period following the encoding of the first stimulus that prevents attending to the second stimulus.
  44. 44. SUBLIMINAL PERCEPTION • Refers to unconscious perception without attention.