Foundations of Perception and Cognition - Attention Part 2 PDF

 This presentation contains images owned by third-parties. They can be used for educational purposes in this presentation. The following copyright warning must be provided prior to presenting them: Copyright Warning This material has been copied and co...

 This presentation contains images owned by third-parties. They can be used for educational purposes in this presentation. The following copyright warning must be provided prior to presenting them: Copyright Warning This material has been copied and communicated under the Statutory Licence pursuant to s113P of the Copyright Act 1968 for the educational purposes of the University of Adelaide. Any further copying or communication of this material by you may be the subject of copyright protection.  Part 1 (Lecture 1) Part 2 (Lecture 2) Focussed vs. Divided Attention Visual Attention and Object Perception World War 2 and Attention Distractions & Perceptual Load Focussed Auditory Attention Inattentional Blindness and Perceptual Load Focussed Visual Attention Divided Attention Recommended Reading This week’s recommended reading is: Goldstein Chapter 4: Attention I discuss most major topics but…. I don’t always cover them in the same order, and I also cover interesting studies / theories that are missing from the chapter Visual Attention and Object Perception If you recall, visual attention is like a spotlight, but the spotlight can take the shape of objects Research suggests that visual attention plays a suprisingly important role in object perception In this section, a theory outlining its role is discussed (Feature Integration Theory) Feature Integration Theory: A Quick Summary Feature Integration Theory (Treisman & Gelade, 1980) differentiates processing object features (colour, shape, etc) from object perception This makes sense as, when we see objects, different brain areas process different features When seeing this image, one brain area Attention ‘binds’ these features, so we have an processes colours (e.g., red) and one integrated perception of an object (called binding) processes shapes (e.g., round) Feature Integration Theory: An Example Suppose I asked you to find the green circle amongst the images on the right Feature Integration Theory suggests you pass through two processing stages to achieve this 1. The Pre-attentive Stage 2. The Focussed Attention Stage Both stages are described in detail next Feature Integration Theory: An Example Stage 1 (Pre-attentive stage): Individual features of all visible objects (e.g., colour, shape) are processed in parallel and are not yet associated (e.g., ‘green’ and ‘circle’ are not associated) Object’s features are therefore ‘free floating’ and any could potentially become associated (e.g., ‘blue’ & ‘circle’, or ‘orange’ & ‘triangle’) Feature Integration Theory: An Example Stage 2 (Focussed Attention Stage): We attend to objects with features matching the one being searched for (i.e., green or circle) Object knowledge helps identify which features to bind (e.g., we know the circle is green, or bananas are yellow) and attention provides a ‘glue’ that binds the features into one integrated percept Feature Integration Theory Predictions Feature Integration Theory’s suggestion that object perception is a two-stage process sounds counterintuitive. Indeed, Triesman and Gelade (1980) agreed it sounds “quite implausible” (p.99). The theory, however, makes several testable predictions One is that if a person cannot focus attention on objects, they will be able to process individual features but will lack the ‘attentional glue’ needed to correctly bind those features into one complete percept What evidence is there to support Feature Integration Theory? Feature Integration Theory: Evidence Treisman and Schmidt’s (1982) participants saw displays with two numbers and four shapes for 1/5 of a sec. This is too fast to focus visual attention to all objects. Participants always reported the black numbers first (so they focussed attention on them) and then described four shapes. On nearly 20% of the trials, they described shapes with an incorrect combination of features (e.g., a yellow triangle). These incorrect combinations are called illusory conjunctions Feature Integration Theory: Evidence In class (time permitting), we will try Treisman and Schmidt’s (1982) experiment out. I have never tried this in a class before, but let’s see if we can get some illusory conjunctions ☺ You will see displays like the one below flashed very briefly and will need to write down the black numbers first (3 and 8), followed by the letters (e.g., Blue T, Red S, Green X). Evidence for Feature Integration Theory Robertson et al. (1997) studied Patient R.M., who developed focussed visual attention problems after two strokes (he could not focus on objects) He could process individual object features but had trouble binding features correctly (e.g., if presented with a Red S and Blue T for 10 secs, he reported ‘illusory conjunctions’ such as “Red T”) More Evidence For Feature Integration Theory Robertson et al. (1997) also found Patient R.M. could easily find targets in displays when only a single feature search was required (e.g., finding a single red letter amongst lots of blue letters) Patient R.M., however struggled finding targets that could only be identified based on a combination of features (e.g., finding a red letter ‘S’ amongst red T’s and blue S’s). This is called a conjunction search Focussed Attention and Distractions When completing a task requiring focussed attention, there may be irrelevant distractions nearby (e.g., sounds, visual stimuli) Distractions can impact task performance: McEvoy et al. (2006) found 6% of drivers attributed crashes to external distractions Hall et al. (2022) found accidents increase (seeing a person/object/event outside the car) after dynamic road signs are installed Researchers have examined the extent to which distractions disrupt task performance Lavie’s Perceptual Load Theory (1995, 2010) Lavie’s Perceptual Load Theory tries to explain how likely we are to be impacted by distractions during focussed attention tasks. It argues: 1. We have limited attentional resources 2. Task-relevant information is processed before task-irrelevant information 3. If a task requires all our attentional resources, distractions may not be processed Nillie Lavie Lavie’s Perceptual Load Theory Lavie’s theory centres on how much attention the ongoing task requires. She differentiated between: 1. Low perceptual load tasks: These require very few attentional resources, so we have resources left over to process distractions. The distractions may impair primary task performance. 2. High perceptual load tasks: These require most or all our attentional resources, so we have few or no attentional resources left over to process distractions and may ignore them. What evidence is there to support this theory? More Evidence For Perceptual Load Theory Forster and Lavie (2008) showed participants letter displays. They had to press a button as quickly as possible if an X or N appeared  Low perceptual load task (left): The X or N was surrounded by one type of letter  High perceptual load task (right): The X or N was surrounded by different letters So, what was the distraction? See the next slide Evidence For Perceptual Load Theory On 10% of trials, a large cartoon character appeared above or below the letters All participants noticed the cartoon character and had slower reaction times on the main task This impairment, however, was only statistically The blue bars show the extra time taken significant in the low perceptual load condition. when the distracting character appeared Perceptual Load Problems One criticism of perceptual load theory is that: “Perceptual load is a vague term that has never been clearly and precisely defined and its consequent operationalizations have been guided primarily by intuitions rather than by a priori rigorous rules” (Benoni & Tsal, 2013) “a key criticism of load theory is the poor definition of “perceptual load” itself. In order for load theory to be advanced, a clear, operational definition of “load” must be agreed upon. Until a clear consensus on load is reached, it remains impossible to endorse or refute experimental results with certainty” (Murphy et al. 2016)  Next, I will discuss inattentional blindness and perceptual load In class, I will show a 2.5 min video demonstrating this effect When watching, you have to decide if an American football was kicked between two posts or not This video below shows stimuli from Simons and Chabris’s (1999) famous inattentional blindness study Many students have seen this before. If you haven’t, watch it now (link below). It shows two teams passing a basketball around. Count the passes the team in white makes (ignore the team in black) https://youtu.be/vJG698U2Mvo What is Inattentional Blindness? Inattentional blindness occurs when we fail to notice unexpected salient objects or events when viewing a scene It occurs as attention is divided and directed away from the unexpected objects/events In Simons and Chabris’s (1999) Gorilla study, 42% of participants did not notice the gorilla Inattentional Blindness in the Real World Drew et al. (2013) had 24 radiologists examine lung X-rays for nodules (non-cancerous growths) The detection rate was only 55% In some X-rays, Simons and Chabris (1999) gorilla was inserted. It is 48 x larger than the average nodule. Only 4 of 24 radiologists (17%) noticed it! Eye-tracking data showed most looked directly at the gorilla. Inattentional blindness occurred Factors Influencing Inattentional Blindness Several factors determine whether inattentional blindness occurs, including:  Unexpected object/task similarity: Simon and Chabris (1999) found 83% of participants saw the black gorilla if counting the black team’s passes  Perceptual Load: Lavie suggested inattentional blindness is most likely to occur when engaging in high perceptual load tasks (e.g., Cartwright-Finch & Lavie, 2007) What evidence is there to support Lavie’s suggestion? Evidence 1 Cartwright-Finch and Lavie (2007) briefly flashed crosses onscreen. The cross arms were different colours and slightly different lengths.  Low perceptual load condition: Participants had to indicate which cross-arm was blue  High perceptual load condition: Participants had to indicate which arm was longer On every 6th trial, something unexpected happened….. Evidence 1 On every 6th trial, a square appeared alongside the cross (participants were not expecting this).  Low perceptual load condition: 55% of participants noticed the square  High perceptual load condition: 10% of participants noticed the square Evidence 2 Murphy and Greene (2016) had participants perform gap perception tasks in a driving simulator, where they had to decide if their vehicle could fit between two parked vehicles they were approaching:  Low perceptual load condition: The gap was clearly big enough  High perceptual load condition: That gap was either just the right size or slightly too small, so participants had to really study the gap whilst driving towards it On 2 of 70 trials, something unexpected happened…. Evidence 2 On 2 of 70 trials, a pedestrian or animal unexpectedly appeared on roadside. Participants were later asked if they saw anything unusual on those two trials:  Low perceptual load condition: 54% of participants noticed the pedestrian/animal  High perceptual load condition: 17% of participants noticed the pedestrian/animal Evidence 3 Murphy and Greene’s (2017) participants completed a driving simulator task, where they had to find a red sports car amongst parked cars  Low perceptual load condition: The was only one red car amongst the parked cars  High perceptual load condition: There were many red cars (but the only sports car) On 8 out of 108 trials something unexpected happened…. Evidence 3 On 8 out of 108 trials, unexpected sounds were played (e.g., screeching tyres) or unexpected stimuli appeared (e.g., a swerving car) Participants were asked to report any unusual sounds or stimuli during trials Participants in the high perceptual load condition were far less likely to notice unexpected stimuli Studying Divided Attention Divided attention is studied via the dual-task paradigm. Studies contain at least two conditions: 1. Focussed attention condition: Participants performs two tasks separately 2. Divided attention condition: Participants perform the above two tasks at once Task performance in both conditions is compared Divided Attention and Driving Attention researchers have examined the impact of secondary tasks on driving, including:  Talking to passengers  Using a handheld or handsfree mobile phone  Using in-built entertainment systems David Strayer’s work has an international impact. Prof. David Strayer, whose research is In class, we will watch a 3 min video on this discussed on p. 112 of Goldstein The Importance of Stimuli Modality When dividing attention between two tasks, the modality of each stimulus being focussed on matters (e.g., whether we are focussing on two visual stimuli, or one visual and one auditory stimuli) Treisman and Davies (1973) had participants monitor word lists for targets (words ending in ‘end’, such as pretend). Each time a target appeared, they pressed a button: Attention Conditions Target Detection Focussed One visual or one auditory list Best (circa 90%) Divided Two visual lists at once Poor (circa 40%) Divided Two auditory lists at once Poor (circa 55%) Divided One visual/one auditory list at once Better (circa 75%) The Importance of Response Modality When dividing attention between two tasks, each task’s response modality matters (e.g., if two tasks require separate manual responses, relative to one requiring a manual/one requiring a verbal response) McLeod (1977) had participants complete tasks with two response types:  Task 1: A game using a controller to keep a dot near a target (manual response with one hand)  Task 2: Responding to high- or low-pitched tones (verbal or manual responses with free hand) Performance on Task 1 was worse if Task 2 also required manual responses Divided Attention and Practice Spelke et al. (1976) showed divided attention improves with practice. They had participants 1. Read a story silently 2. Write down spoken words (dictation) 3. Read a story & write down spoken words Individual task performance was good but dual- task performance poor (e.g., slow reading) Continued next slide Divided Attention and Practice Spelke et al.’s (1976) participants then practiced the dual-task for 5 hours week for 4 months ▪ 6 weeks practice: They could read/dictate at the same time without impairment on either task ▪ 16 weeks practice: They could do easily perform both at once and place the words in appropriate categories (e.g., fruits, animals), showing they could think about the words and engage in decision making without compromising performance Conclusion: Practice improved divided attention/dual-task performance Divided Attention and Aging “one of the best exemplars of a mental activity in which large and robust age-related differences have been consistently obtained is dual-task processing” (Kramer & Larish, 1996, p. 106) Verhaeghen et al. (2001) meta-analysed 63 dual-task studies comparing young adults (M = 30 years old) and older adults (M = 60 years old): ▪ Reaction time studies: Older adults were slower ▪ Accuracy studies: Both had similar levels of accuracy Conclusion: Older people have slower processing speeds (if dividing attention) but are no less accurate By the end of Attention: Part 2, you should be able to: 1. Explain the role that visual attention plays in object perception 2. Explain what perceptual load is, what high and low perceptual load tasks are, and how they impact the likelihood of being distracted during a task 3. Explain what inattentional blindness is and how it is impacted by perceptual load 4. Explain the factors that determine how effective we are at dividing attention between two tasks