1. © 2010 by W. W. Norton & Co., Inc. Paying Attention Chapter 4 Lecture Outline

2. © 2010 by W. W. Norton & Co., Inc. Chapter 4: Paying Attention Lecture Outline  Selective Attention  Divided Attention  Practice

3. © 2010 by W. W. Norton & Co., Inc. Selective Attention Selective attention refers to the skill through which one focuses on one input or one task while ignoring other stimuli.

4. © 2010 by W. W. Norton & Co., Inc. Selective Attention Attention studies sometimes employ a task known as shadowing.  Using headphones, different information is presented to each ear. This is known as dichotic listening.  The participant pays attention to the information presented to one ear (the attended channel) while ignoring information presented to the other (the unattended channel).

5. © 2010 by W. W. Norton & Co., Inc. Selective Attention Results from these studies suggest that unusual characteristics of the unattended channel go unnoticed. Similar effects happen in visual studies, e.g., in a classic study, participants asked to count the number of basketball passes failed to notice a person in a gorilla suit enter the scene.

6. © 2010 by W. W. Norton & Co., Inc. Selective Attention There are some important exceptions, where certain pieces of information will be noticed even if presented to the unattended channel.  The participants own name, or any words of high personal significance, will be noticed even in the unattended channel. This pattern is observed in real-life situations and sometimes called the cocktail party effect.

7. © 2010 by W. W. Norton & Co., Inc. Selective Attention Sometimes effects of attention are so strong that we fail to see stimuli that are directly in front of our eyes. For instance, if participants are asked to look at a fixation target while attending to another part of the screen, they may fail to notice changes in shape to the fixation target. This phenomenon is known as inattentional blindness.

8. © 2010 by W. W. Norton & Co., Inc. Selective Attention A phenomenon similar to inattentional blindness occurs when a distracted person cannot find something in the refrigerator, even if it is directly in front of the eyes.

9. © 2010 by W. W. Norton & Co., Inc. Selective Attention From studies of inattentional blindness, one might be tempted to conclude that there is “no perception without attention.” However, other studies demonstrate that unconscious perception still occurs in the absence of attention.

10. © 2010 by W. W. Norton & Co., Inc. Selective Attention For example, participants’ judgments of line length are influenced by the presence of “fins” that cause the Müller-Lyer illusion, even if they do not consciously see the fins.

11. © 2010 by W. W. Norton & Co., Inc. Selective Attention Other studies of attention focus on a phenomenon known as change blindness, the inability of observers to detect changes in scenes they are looking directly at. See if you can detect the differences between the following pairs of pictures:

12. © 2010 by W. W. Norton & Co., Inc. Selective Attention

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17. © 2010 by W. W. Norton & Co., Inc. Selective Attention

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21. © 2010 by W. W. Norton & Co., Inc. Selective Attention Similar effects of change blindness occur when people fail to notice continuity errors in films. In a particularly striking example, participants failed to notice when the person asking them for directions changed identity (following a brief interruption by two people carrying a door).

22. © 2010 by W. W. Norton & Co., Inc. Selective Attention Early studies of attention focused on when the perceiver selects the desired input. According to the early-selection hypothesis, the unattended input receives little to no analysis. According to the late-selection hypothesis, all input receives analysis but only the attended input reaches consciousness or is remembered.

23. © 2010 by W. W. Norton & Co., Inc. Selective Attention Both the early- and late-selection hypotheses capture part of the truth.  For instance, the study discussed earlier showing that unattended stimuli have effects on perception seems to be a case of late selection.  However, the electrical activity of the brain for attended versus unattended inputs differs within 70 ms of stimulus presentation, suggesting early selection.

24. © 2010 by W. W. Norton & Co., Inc. Selective Attention An experiment by Posner and Snyder (1975) illustrates that there are two kinds of priming related to attention. One kind of priming is stimulus-based, the other is expectation-based. For this type of study, the dependent variable is the response time to make a decision about the stimuli.

25. © 2010 by W. W. Norton & Co., Inc. Selective Attention

26. © 2010 by W. W. Norton & Co., Inc. Selective Attention Posner and Snyder (1975) found in the low-validity condition that the primed condition was faster than neutral.  This demonstrates an effect of repetition priming; the receptors were “warmed up.” But, the misled condition was not any slower than neutral.  Warming up the “wrong” detector does not take activation away from the correct one.

27. © 2010 by W. W. Norton & Co., Inc. Selective Attention Posner and Snyder (1975) found in the high-validity condition that the primed condition was much faster than neutral.  This demonstrates an additional effect of expectation in addition to repetition priming. Further, the misled condition was slower than the neutral condition.  Expectation is limited in capacity; the “wrong” expectation interferes with activating the correct detectors.

28. © 2010 by W. W. Norton & Co., Inc. Selective Attention Studies of spatial attention examine the ability to focus on a particular position in space and to be prepared for stimuli appearing in that position.

29. © 2010 by W. W. Norton & Co., Inc. Selective Attention For example, when detecting a stimulus on the right or left side of the screen, participants benefit if an arrow provides a cue indicating on which side the stimulus is about to appear (Posner et al., 1980). Note that directing spatial attention is different than moving the eyes.

30. © 2010 by W. W. Norton & Co., Inc. Selective Attention Spatial attention is sometimes thought of as a “searchlight.” We can move this searchlight in space, as well as adjust the size of the “beam.”

31. © 2010 by W. W. Norton & Co., Inc. Selective Attention Do we attend to positions in space or to objects? Evidence from unilateral neglect syndrome, caused by damage to the right parietal lobe, could be argued to support a space-based view. These individuals cannot attend to the left side of space. However, some experiments suggest that the deficit is also object-based.

32. © 2010 by W. W. Norton & Co., Inc. Selective Attention Unilateral-neglect patients attended to the red circle, initially presented on the right, even after it rotated to the left side of the object. Healthy participants also show a mixture of spatial and object- based attention.

33. © 2010 by W. W. Norton & Co., Inc. Selective Attention Summary of selective attention:  Attention involves both facilitating the processing of desired input and inhibiting the processing of unwanted input.  Attention can be directed to both what the object is as well at where it is in space.  There is some flexibility in when the effects of attention will take place (early or late).  What we think of as attention is not a single process or a particular mechanism.

34. © 2010 by W. W. Norton & Co., Inc. Divided Attention Divided attention refers to the skill of performing multiple tasks simultaneously. This is only possible when the sum of the tasks’ demands is within the “cognitive budget.” Julius Caesar was praised for his ability to multitask.

35. © 2010 by W. W. Norton & Co., Inc. Divided Attention Some cognitive resources are specialized.  For instance, verbal and spatial tasks can sometimes be performed spatially because each draws upon different resources.

36. © 2010 by W. W. Norton & Co., Inc. Divided Attention Other cognitive resources are general.  For instance, speaking on a cell phone (even with a hands-free device) interferes with the ability to drive, even though the two tasks are seemingly very different.

37. © 2010 by W. W. Norton & Co., Inc. Divided Attention Several task-general cognitive resources have been proposed, such as:  A response selector that is required for selecting and initiating responses, both physical and mental.  A central executive that sets goals and priorities, chooses strategies, and directs the function of many cognitive processes.

38. © 2010 by W. W. Norton & Co., Inc. Divided Attention Executive control is strongly connected with working memory. It is also believed to inhibit automatic or habitual responses when a situation requires a novel response. Kane et al. (2001) found that individual differences in working memory did not predict the ability to move the eyes towards a cue (the automatic response), but did predict the ability to move the eyes away from a cue (a novel response).

39. © 2010 by W. W. Norton & Co., Inc. Practice As a task becomes more practiced, it requires fewer cognitive resources. As the ability becomes more automatic, executive control and the response selector are needed less and less.

40. © 2010 by W. W. Norton & Co., Inc. Practice Why does practice improve performance?  Complex tasks – like playing tennis, playing the piano, or driving a car – can by themselves create problems in divided attention.  With practice, components of the task change from being a controlled process to being an automatic one.

41. © 2010 by W. W. Norton & Co., Inc. Practice Controlled tasks are novel and require flexibility in one’s approach.  These tasks require attention and cannot be carried out if the person is busy with another task. Automatic tasks are well practiced and do not require flexibility.  These tasks require little or no attention and can be carried out if the person is also busy with another task.

42. © 2010 by W. W. Norton & Co., Inc. Practice The downside of automaticity is seen in tasks that require the participant to override an automatic response. The Stroop task illustrates the high automaticity of reading. Try to name the ink color and do not read the word.

43. © 2010 by W. W. Norton & Co., Inc. Practice In this variant of the Stroop task, try to identify how many symbols are present in each row. This also illustrates the automaticity of reading the numbers.

44. © 2010 by W. W. Norton & Co., Inc. Practice Summary of divided attention and practice:  Tasks require resources, and you cannot “spend” more resources than you have.  Some resources are task-specific, and others are task-general.  If two tasks make demands upon the same resources, the result will be interference.  Practice increases the automaticity of a task, resulting in the need for fewer cognitive resources.