PSYC 441 Cognitive Psychology II

Transcription

1 PSYC 441 Cognitive Psychology II Session 8 Attention Lecturer: Dr. Benjamin Amponsah, Dept., of Psychology, UG, Legon Contact Information: bamponsah@ug.edu.gh College of Education School of Continuing and Distance Education 2014/ /2017

2 Session Overview I am going to introduce to you yet another basic process in Cognition, that is attention. It is concerned with how we manage to mentally focus on some things in the environment and how we tune out others. Attention may be seen as a link between the enormous amount of information that impinges on our senses and the limited amount that we actually perceive. It enables us to perceive things we need to be aware of and how we ignore others. Slide 2

3 Session Objectives At the end of the session, the student will be able to Explain the cognitive process of attention Explain the various theories that have been proposed to explain selective attention Review some neuropsychological studies of attention Slide 3

4 Session Outline The key topics to be covered in the session are as follows: Topic One: Paying Attention Topic Two: Basic Research on Attention Topic Three: Structural (Bottleneck) Models of Attention Topic Four: Capacity (Resource) Models of Attention Slide 4

5 Reading List Ashcraft, M. H. (2013). Cognition (6 th edn.), London: Pearson Education Int. Eysenck, M. W. (2012). Fundamentals of Cognition (2ed). Psychology Press, Sussex. Galotti, K. M. (2017). Cognitive Psychology: In and out of the laboratory (6 th edn.). Belmont, CA: Wadsworth. Halpern, D. F. (2013). Sex differences in cognitive abilities (2ed). Lawrence Erlbaum Ass. NJ. Hunt, R. R. & Ellis, H. C. (2004). Fundamentals of Cognitive Psychology (7 th edn.), New York: McGraw-Hill. Willingham, D, B. (2013). Cognition: The thinking animal (International edn. NJ: Prentice-Hall). Slide 5

6 Topic One PAYING ATTENTION Slide 6

7 Paying Attention Attention is concerned with how we manage to mentally focus on some things in the environment and to tune out others. Attention here may be seen as the link between the enormous amount of information that impinges our senses and the limited amount that we actually perceive. In other words, attention enables us to perceive things we need to be aware of and how we ignore others. It is also equally true that sometimes our attention wanders and we are also able to divide our attentional resource in performing several things simultaneously. Slide 7

8 Paying Attention In everyday life, we are bombarded and exposed to more information than we can process. Examples: We pay attention to sound, vision, touch, smell and taste etc. Consider driving compare your first time experience to your level of proficiency. There seems to be some savings with your time and energy in doing the same task. Cognitive psychologists interested in attention studies are concerned with availability of Mental Resources and their limitations. Complexity and unfamiliarity of the task require more mental resources. Slide 8

9 Attention simply refers to the concentration and focusing of mental effort a focus that is selective, shiftable and divisible (Maltin, 1983). Lets consider the key concepts: Selective because we don t process everything that impinges on our sensory system. Shiftable because we can shift our attention from one item to the other. Divisible because we can divide it into parts to attend to several jobs (multitasking). With practice, concentration level changes and we can perform other tasks simultaneously. Slide 9

10 BASIC FACTS OF ATTENTION 1. We are constantly confronted with much more information than we can pay attention to. 2. There are serious limitations to how much we can attend to at any given time. 3. We respond to some information and perform some tasks with little attention. 4. With sufficient practice and knowledge, some tasks become less and less demanding of our attentional process. Slide 10

11 Topic Two BASIC RESEARCH ON ATTENTION Slide 11

12 Basic Research on Attention Several studies reported in the late 1950s showed that attentional processes play important role both in what people perceive, what they store and in what they remember. Let s look at one of the interesting phenomena they handled. The Cocktail Party Phenomenon Colin Cherry (1953) set the stage for the modern study of attention by describing the cocktail party phenomenon (which describes how people respond when confronted with several simultaneous conversations as they are at a cocktail party or similar social gatherings). Slide 12

13 At such gatherings, you can selectively attend to one among many conversations going on around you. However, at the same time as you seem to ignore other conversations from others, you sometimes notice certain events, such as when your name is being mentioned in one of the ignored conversations. One important aspect of the cocktail party phenomenon deals with a process called selective attention, which is the ability to attend to one of several streams of information. The second aspect of the phenomenon reflects divided attention, which is also the processing of more than one stream of information at a time. Divided attention is evident when we suddenly become aware of personally relevant information, such as our name, in a conversation we thought we were ignoring. Slide 13

14 Auditory Events and Selective Attention The term selective attention refers to the fact that we usually focus our attention on one or a few tasks or events rather than on many. To mentally focus implies that we shut out (or process less information) from competing tasks. So what happens to the information we don t pay attention to? (The fate of the unattended stimuli). How do cognitive psychologists study information people process about things to which they don t pay attention to? Are we aware of such unattended information in the first place? Can we instruct people in an experiment not to pay attention? Would it be effective if we do so? Slide 14

15 Fortunately, cognitive psychologists have devised a solution known as - Dichotic Listening Task (DLT) a task in which a person hears two or more different, especially recorded messages over earphones and is asked to shadow one of them. (Shadow here means reciting a message played over stereo headphone as you listen to it). Slide 15

16 In a speech-shadowing task used by Cherry (1953), the two messages are played to the listener simultaneously and the listener repeats word for word the message in the attended ear. Slide 16

17 Dichotic Listening Task In one of the important studies on selective attention in the auditory domain, Cherry (1953) used a dichotic listening task. In this task, information is presented at a rapid rate of 150 words a minute (shadowing task is demanding, because it needs concentration and a great deal of mental resources). At the end of the experiment or shadowing task, participants are asked what information they remember from either message the attended (shadowed) or the unattended (nonshadowed) message. Slide 17

18 Findings According to Cherry (1953), people are capable of: Shadowing a spoken message with few errors. When asked about the unattended messages too, they were able to report accurately whether the messages contained speech or noise, If speech, whether the speaker was a man or a woman. But the subjects could not recall the content of the unattended message or the language in which it was spoken. In similar experiment by Moray (1959), his subjects failed to recognize in a prose the occurrence of most of the words in the unattended message, even though the list was repeated 35 times! Slide 18

19 Visual Shadowing What about Visual Events? (Visual Shadowing) In visual shadowing the same inattention can be repeated. Neisser and Becklen (1975), created a visual task similar to the speech-shadowing task by videotaping a two very different events and then combining them into a single video in which the two events were superimposed (see Figure). The subjects were asked to follow the action in one of the events. To enable them focus their attention on one scene, they were instructed to press a button whenever an unusual event occurred in the scene they were watching. Slide 19

20 A Selective Looking Task Neisser and Becklen (1975) used video displays to study a selective looking. Original scenes of (a) a hand-slapping and (b) a basketball game were superimposed in (c). Slide 20

21 The results showed that when subjects attend to one scene, they don t notice what is going on in the other scene. For example, only one subject out of the 24 who focused on the basketball scene noticed that midway through the tape the players of the hand-slapping game stopped their game and shook hands. Just like in the speech-shadowing experiments, people attend selectively to one stream of information and ignore others. Slide 21

22 Topic Three STRUCTURAL MODELS OF ATTENTION Slide 22

23 Structural Models Cherry and Moray support the idea that there is a limitation on the amount of information humans can process. A general explanation is that this limitation is caused by a structural bottleneck somewhere in the information processing system. Three general types of structural models (sometimes called Bottleneck Theories) identify the bottleneck or capacity limitations in the information processing stages. 1. Early selection models attention is the bottleneck that limits the perceptual analysis of stimuli. If items are not attended to, they are not selected for perceptual analysis and are subsequently lost from the system. Slide 23

24 Structural Models 2. Treisman s Attenuator Model the unattended items in the information processing stages are attenuated and for that matter are available for recognition. 3. Late selection models suggest that all stimuli are initially selected and perceptually analyzed. It suggests that the limit on attention occurs after perceptual analysis, when the person uses that information to select a response. Slide 24

25 Structural Models Early Selection Models Several influential models were proposed in the 1950s and 1960s that had enormous impact on the study of attention and on cognitive psychology generally. Broadbent s Filter Theory Donald Broadbent (1958) developed an influential model of selective attention. The model was significant in the history of cognitive psychology for two important reasons. His model was the first flowchart model of human information processing and thus represented a major departure from earlier psychological models which mostly emphasised associations between stimuli and response from the behaviourists. Slide 25

26 The second was that, his model contained the seeds of its own destruction. The model was easily testable and researchers were soon able to show that some elements of the model were wrong. The theory (Broadbent) states that: The amount of information that can be attended to at any given time is limited. Therefore, if the amount of information available at any given time exceeds capacity, an attentional filter is used to let some of the information get through and the rest blocked. Slide 26

27 Broadbent s filter model has several important characteristics: First the filter selects information on the basis of the physical characteristics of the stimulus (e.g., pitch, tone). The filter operates in an all-or-none fashion. Those that are not attended to are blocked. The filter operates like a channel selector on television. There are so many channels operating, only the one selected is processed and displayed on the screen, the other channels are blocked. The filter is under conscious control. People decide what stimulus to process and can switch from one stream of information to another. Slide 27

28 After a stimulus is selected for further processing, it is passed along to the limited-capacity P-system (perceptual system). Filter model of attention. Different incoming messages shown as arrows, all arrive at the same time. The filter (line inside the box) blocks all but message 2, which goes on for further cognitive processing. Slide 28

29 BROADBENT FILTER THEORY BROADBENT FILTER THEORY Slide 29

30 What do we learn form this theory? The theory though criticized heavily is able to explain so many important aspects of attention phenomenon to us. The theory explains why so little meaning of the unattended message can be recalled. The theory maintained that the attentional filter is set to make a selection of what message to process early in the processing, before meaning of the message is identified. The filter model has adaptive function in that it serves to protect us from information overload by shutting out messages when there is too much information to process all at once. Slide 30

31 Other investigators soon reported results that contradicted the filter theory. For cocktail party effect (that is, people s shadowing performance is disrupted when their own name is embedded in either the attended or unattended message) to show the weaknesses of the filter model of Boadbent. Why does the cocktail party effect pose a problem for filter theory? Slide 31

32 Filter theory predicts that all unattended messages will be filtered out (not processed for recognition). But the cocktail party phenomenon showed that not all unattended messages are filtered and we can hear our names, words of subjective importance like fire, danger and so on, when we are not attending originally to that message. Slide 32

33 Treisman s Attenuation Theory The apparent weaknesses in the Broadbent s model are addressed by Treisman (1960) in proposed modified filter theory called Attenuation theory. Treisman suggested that instead of considering the unattended messages to be completely blocked (all-or-none) before they could be processed for meaning (as in filter theory), she argued that their volume was turned down. This allows the unattended message to pass along in an attenuated or weakened form. In other words, some meaningful information in the unattended messages might still be available. Slide 33

34 Schematic representation of attenuator model in which Message 1 is attended and in which some of Message 2 also gets through for further processing Slide 34

35 Attenuator Model ATTENUATOR MODEL BY TRIESMAN Slide 35

36 According to Treisman, incoming messages are subjected to three kinds of analysis: 1. The message s physical properties, such as pitch, or loudness are first analyzed. 2. The second analysis is linguistic a process of parsing the message into syllables and words 3. The third analysis is semantic processing the message for meaning. Slide 36

37 Within this scheme, some meaningful units (words or phrases) tend to be processed quite easily. Words that have subjective importance like: your name fire! danger! watch out!, etc have lowered thresholds that are easily recognized or may filter through at low volumes. The context of a word in a sentence can also lower its threshold. E.g., at Legon, Vandals and commonwealth hall, this process is referred to as semantic priming (refers to the fact that if the stimulus preceding the current stimulus is semantically related response to the current stimulus is affected). Slide 37

38 In sum, the attenuator model proposes that the unattended messages are not completely blocked, but are rather weakened in much the same way as turning down the volume of a stereo weakens its signal. Thus, according to Treisman s theory, the participants in Moray s experiment heard their names because recognizing their names required little mental effort due to its lowered threshold. Slide 38

39 Contrast between Filter and Attenuation theories. Attenuation theory allows for different kinds of analyses of all messages received (physical, linguistic and semantic), whereas, filter theory allows for only one (all-or-none affair). Filter theory holds that unattended messages, once processed for physical characteristics, are discarded and fully blocked; Attenuation theory holds that unattended messages are weakened but that the information they contain is still available. Slide 39

40 Late Selection Theory Deutsch and Deutsch (1963) proposed the Late Selection Theory which goes further than the theories we have reviewed. The theory postulates that all incoming stimuli are processed and that subjects should be able to recognize information under almost any circumstances, even when information is presented to a nonshadowed ear. This is because, we cannot voluntarily choose to identify or recognize something. Slide 40

41 Slide 41

42 Summary of the Bottleneck Theories Three models of attention and capacity in sensory processing. The models also show the stages at which detection takes place. Slide 42

43 Topic Four CAPACITY (RESOURCE) MODELS OF ATTENTION Slide 43

44 Resource Models You learned about some of the structural models of attention in their attempt to explain the fate of the attended and the unattended stimuli. We looked at the history and the grounds to compare the bottleneck theories (Broadbent, Triesman and Deutsch & Deutsch) We now proceed with more current theories that explain attention generally. These theories are sometimes referred to as Resource Models of attention because largely, they emphasise on our capacity and cognitive resources available to process information. Slide 44

45 Overview The bottleneck theories of attention were so popular in the 1950s but soon researchers became disenchanted because of their apparent weaknesses and their inability to explain the fate of the unattended stimuli. Several researchers have abandoned the idea of a filter model and have suggested we instead view attention in terms of allocation of cognitive effort or processing resources. While the filter models were viewed as structural models because they described structures such as channels and filters, the models of the 1970s and 1980s are characterised as capacity or resource models of attention. These are: multimode theory, Schema and Kahneman s capacity models. Slide 45

46 Multimode Theory Critically, the Filter theory doesn t quite explain why some messages in the unattended channel become noticed. On the other hand, strict late-selection theory encounters a problem because if all messages are processed simultaneously for meaning, why are some messages blocked? A model that incorporates (filter and attenuation) is proposed as the multimode theory by Johnston and Heinz (1978). They identified 3 stages of in information perception. Stage 1 is the initial stage where sensory representations of stimuli are recognized. Slide 46

47 Stage 2 is the stage where semantic representations (meanings) are constructed. Stage 3 is the stage where sensory and semantic representations enter consciousness. Their analysis at Stage 1 corresponds to that of Broadbent early filter theory while Stage 3 corresponds to Deutsch and Deutsch s late selection model. According to these researchers, processing at the third Stage (sensory + semantic) requires more capacity and mental effort than at the first stage (sensory). A simple experiment to test their theory (Johnston & Heinz, 1978). Slide 47

48 Subjects performed two tasks simultaneously. The first was a standard Dichotic Listening Task. Subjects listened to a message in which the sex of the speaker was varied (The sex of the speaker presenting the message sometimes differed - facilitating early selection). Note the initial, pitch or tone are raw and are detected early in time. At other times, the same speaker presented both messages - which differed in meaning (requiring late selection). The second task involved detecting and responding as quickly as possible to randomly presented lights by pressing a key (signal detection). Slide 48

49 They reasoned that the more attention required by the listening task, the less processing capacity would be available for other tasks. They predicted that fewer resources would be available and participants would react more slowly in pressing the keys. Their predictions were confirmed. The subjects responded quickly to the light when they had to detect the sex of the speaker based on sound. Response to the light was slower when they had to select a message based on meaning. Slide 49

50 In sum, pressing light was quicker when they were detecting sex of the speaker and were slower when they processed for meaning, suggesting capacity limitation. Slide 50

51 Schema Theory Ulric Neisser (1976) offered a completely different conceptualization of attention. He argued that we don t filter, attenuate, or forget unwanted material. In fact, we don t even acquire it in the first place. He compared attention to apple picking. The attended materials are the apples we pick off a tree. The unattended material is analogous to the apples we don t pick. To assume that the unpicked apples were filtered out is ridiculous - a better description is that they were left on the tree or left out of our cognitive processing. The difficulty here is that we are still aware of the unripped apples left on the tree. Slide 51

52 Capacity Models of Attention Capacity Models of Attention The impact of the capacity model occurred when David Kahneman published his model in a book in The book summarised the empirical findings on attention from the cognitive psychology literature and included a model that deviated markedly from the earlier filter models. Note that the model is designed to supplement rather than supplant the bottleneck positions. According to Kahneman, our psychological resources are finite and at any time, we have limited cognitive capacity to devote to various tasks confronting us. Slide 52

53 Capacity Models of Attention The number of activities we can perform simultaneously is determined by the capacity each task requires. If a single task requires intense concentration and effort, no capacity will remain for additional task. His model, assumes an allocation policy that apportions capacity to the tasks to be performed. The allocation policy is managed by several factors. Slide 53

54 Central Capacity Theory of Kahneman Slide 54

55 Evaluation demands: with the rule that if two activities require more capacity than is available, we decide to perform one and delay the other. Arousal: indicating that performance varies with the state of arousal (e.g., anxiety, fear, anger, sexual excitement, effects of drugs, intense stimulation etc.) Our enduring dispositions. The amount of attention we give to tasks is dependent upon what type of people we are: our personality, our habits and our long-term goals. Our momentary intentions. Some stimuli may receive more attention than others because they are deemed more relevant to the task, the context we are in can affect what we attend to and our current mood or personal concerns can affect what we attend to and what we choose to ignore. Slide 55

56 Resource-Limited and Data-Limited Processes Related to the work of Kahneman (1973), Norman and Bobrow (1975) have claimed that our performance in any situation is under two types of constraints. These are: Data-limited or Resource- limited tasks. Data-limited tasks are those which are difficult or impossible even if we devote all of our processing resources to the task. E.g., you are suddenly asked to land a jetliner because all crew members are sick. In spite of intense concentration, performance is limited by the quality of data. Slide 56

57 Resource-limited tasks are those on which performance can be improved by increasing the amount of processing. E.g., taking detailed notes from slides and trying to understand a lecture simultaneously. You may take good notes but may not understand the lecture. In case of data limitation, we are unable to perform because of the poor quality of the information on which to act. It arises due to lack of knowledge or experience. Slide 57

58 Similarity to bottleneck theories Data limitations produce poor performance for the same reason that early-selection filters do information cannot be adequately processed. Resource limitations are analogous to lateselection filters in that performance is limited by the amount of processing devoted to the task. Resource-limited tasks are relevant to the capacity model of attention than Data limited tasks. Slide 58

59 Sample Questions 1. What physical characteristics of a spoken message are likely to affect how well a listener can selectively attend to that message? 2. What are the main assumptions underlying Kahneman s single capacity model of divided attention? How can these assumptions be tested with the dual-task methodology? 3. Why do we call the theories in the 1950s structural models and those of the 1970s and 1980s resource and capacity models? Slide 59

60 References Maltin, M. W. (2002). Cognition (5 th ed.). Thompson, Wadsworth. Cherry, E. C. (1953). Some experiments on the recognition of speech, with one and two ears. Journal of the Acoustical Society of America, 25, Moray, N. (1959). Attention in dichotic listening: Afffective cues and the influence of instructions. Quarterly Journal of Experimental Psychology, 11, Neisser, U., & Becklen, R. (1975). Selective looking: Attending to visually specified events. Cognitive Psychology, 7, Broadbent, D. E. (1958). Perception and communication. New York: Pergamon. Slide 60

61 Treisman, A. M. (1960). Contexual cues in selective listening. Quarterly Journal of Experimental Psychology, 12, Deutch, J. A., & Deutch, D. (1963). Attention: some theoretical considerations. Psychological Review, 70, Johnston, W. A., & Heinz, S. P. (1978). Flexibility and capacity demands of attention. Journal of Experimental Psychology: General, 107, Neisser, U. (1976). Cognition and reality: Principles and implications of cognitive psychology: San Francisco: W. H. Freeman. Kahneman, D. (1973). Attention and effort. Englewood Cliffs, NJ: Prentice Hall. Norman, D. A., & Bobrow, D. G. (1975). On data-limited and resource-limited processes. Cognitive Psychology, 7, Slide 61