Foundations of Perception and Cognition 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. Who am I? Name: Dr. Craig Thorley Job title: Senior Lecturer in Psychology Research focus: Human memory accuracy and age estimation accuracy School Role : Program Director of the Graduate Diploma in Psychology (Online)  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 What is Attention? Attention is the cognitive process of focussing on a task, whilst ignoring distractions Psychologists distinguish between:  Focussed attention: Our ability to focus on one task whilst ignoring distractions  Divided attention: Our ability to focus on Focussed/divided attention have similar two or more tasks at the same time biological bases (frontal/parietal lobes)  Focussed vs. Divided Attention Focussed Auditory Attention Focussed Visual Attention Divided Attention Focussing on one conversation in a noisy Focussing on a scanner for extended Focus on driving, a phone bar when other conversations are periods of time without mind-wandering conversation, and applying occurring nearby, loud music is playing etc or getting distracted by passengers make-up all at once  Studying Focused Attention Focused attention is often studied by presenting participants with two stimuli at once and asking them to focus on one (e.g., listen to two conversations but focus on one/ignore the other) The stimuli is often auditory (focussed auditory attention) or visual (focussed visual attention)* Researchers examine issues such as: 1. How well we can focus attention on one stimulus whilst ignoring another 2. What influences our ability to focus attention on one stimulus (e.g., tiredness?) 3. Whether we process any of the unattended stimulus that is meant to be ignored *Auditory and visual attention function in slightly different ways. The Goldstein textbook does not do a good job of explaining this Studying Divided Attention Divided attention is studied by having participants complete two tasks at once (e.g., focussing on two visual stimuli at once, or focussing on one auditory and one visual stimulus at once) Researchers examine issues such as: 1. How well we can complete two tasks at once A divided attention study where a 2. What influences our ability to do the above participant is having a hands-free (e.g., task modality? task familiarity?) telephone conversation whilst driving Attentional Limitations Our attentional system has limited processing power. This impacts us in several ways. For example: 1. We can struggle focussing on a single task for an extended period 2. We can struggle focussing on two or more tasks at once 3. We can only attend to a small amount of environmental information at once, and can fail to notice salient information, events, or changes in our environment In class, I will show a 3-minute video on ‘change blindness’ demonstrating point 3 WW2 and Attention During WW2, technological advances placed unprecedented demands on human cognition: Focussed Attention: Radar operators had to Divided Attention: Pilots were put in cockpits monitor screens for extended periods of where many dials needed monitoring, whilst time, watching for enemy aircraft. How long also chatting to command and looking for would it take for their minds to wander? threats. Is this too much for one person?  WW2 and Attention The UK military had psychology academics study attention, to ensure personnel were working to the best of their ability:  Examples: Mackworth (1948) developed the ‘Clock Task’ to see how long radar operators can monitor screens before missing information (30 mins!). Others examined pilot’s attention during long operations The research was not published until after WW2 for obvious reasons! WW2 and Focussed Auditory Attention Radar operators during WW2 had to listen to messages from several pilots simultaneously over one loudspeaker. This is a difficult task Colin Cherry and Donald Broadbent wanted to know how well they could focus attention on one message and if they process any of the ignored messages. Cherry (1953) created his famous dichotic listening task to study this….. Broadbent was a trained WW2 pilot The Dichotic Listening Task Cherry’s (1953) participants listened to two messages at once (one in each ear). They were asked to attend to one message / ignore the other. As proof they were doing this, they repeated the attended message aloud (called shadowing). Would participants process one or both messages? In the lecture, I will play audio of a dichotic listening task  The Dichotic Listening Task Cherry’s (1953) later tested participants’ recall of attended and ignored two messages: ▪ The attended message: Participants could easily recall its content ▪ The ignored message: They could describe its To help explain what he was studying, Cherry physical characteristics (i.e., speaker gender, called it The Cocktail Party Problem: How can we focus on one voice at a noisy cocktail pitch) but could not recall any of its content* party when others are also speaking? *Some participants didn’t even notice when the unattended message was in German or reversed (backwards) speech! Broadbent’s (1958) Filter Theory Broadbent tried explaining how focussed auditory attention works. His Filter Theory was based on Cherry’s (1953) findings. The theory was depicted in a flow diagram (see below) 1. When we hear two (or more) messages at the same time, each enters sensory memory 2. They then reach a filter: The message you wish to attend to is identified via physical characteristics (e.g., accent, tone, pitch, speed of talking). All other unattended messages are blocked Broadbent’s (1958) Filter Theory 3. The detector processes the information from the attended message to determine its higher-level characteristics, such as its meaning 4. The detector sends the processed information to short-term memory, which holds information temporarily. It can then move to long-term memory, which can hold information indefinitely This is called an Early Selection Model, as it filters out unattended information at the start Filter Theory Problems Dear, 8, Jane 9, Aunt, 3 Moray (1959): 1/3 of participants heard their own name when it was secretly embedded into an unattended message Gray and Wedderburn (1960): Participants heard words from meaningful sentences and digits. Items alternated between ears (see right). Participants shadowed one ear only Gray and Wedderburn’s (1960) study is but recalled the entire meaningful sentence nicknamed the ‘Dear Aunt Jane’ experiment Filter Theory Problems Summary Broadbent wrongly suggested unattended messages are blocked at the ‘filter stage’ Studies showed information that was supposed to have been filtered out was processed. Two new theories were therefore offered by:  Anne Treisman (1964) – Broadbent’s student Treisman (originally from the UK) received  Deutsch and Deutsch (1963) the US National Medal of Science in 2011  Treisman’s (1964) Attenuation Theory Treisman (1964) amended Broadbent’s (1958) Filter Theory slightly: 1. Both messages enter sensory memory. They reach an attenuator, where the message of interest is identified via physical characteristics and meaning. Unattended message processing is reduced (not eliminated). Both messages are then sent to the Dictionary Unit for further processing. Note: This is also an Early Selection Model as the message of interest/unattended messages are segregated at the start Treisman’s (1964) Attenuation Theory 2. The Dictionary Unit contains words, stored in memory. Each word has an activation threshold: ▪ Common words: High activation threshold (so no special attention paid to them) ▪ Important words (your name, ‘fire’): A low activation threshold (special attention paid to them) If an unattended message has low activation threshold words (or words matching the content of the attended message, as in the ‘Dear Aunt Jane’ study), they receive special attention/reach consciousness  Deutsch and Deutsch’s (1963) Late Selection Model Deutsch and Deutsch (1963)/MacKay (1973) proposed an alternative model, as they suggested all information is fully processed for meaning, without any filtering or attenuation The most relevant information becomes the focus of attention, but we should notice all relevant information in the unattended message (as that message is also fully processed for meaning) Note: This is a Late Selection Model as the message of interest/unattended messages are segregated at the end A Comparison of the Theories Triesman’s Attenuation Theory:  Unattended information reaching consciousness is the exception, rather than the rule (the information must be important/low threshold to reach consciousness) Deutsch and Deutsch’s Late Selection Theory:  Unattended information reaching consciousness is the rule, rather than the exception (if relevant, it will reach consciousness) Which theory has the best support? Which Theory Has Best Support? Treisman and Geffen (1967): Ran a dichotic listening study where participants shadowed one message and tapped the table if they heard a target word (e.g., tree) in the shadowed or unattended message The target word was unimportant/low threshold word. Each theory makes different predictions: ▪ Treisman’s Attenuation Theory: Low target detection in the unattended message ▪ Deutsch and Deutsch’s Late Selection Theory: High target detection in the unattended message The findings supported Treisman’s theory: only 8.1% of unattended message targets were detected. Unattended information reaching consciousness was the exception (not the rule) Summary Treisman’s (1964) Attenuation Theory is best supported, although likely needs refinements:  Neurologically, in cocktail party scenarios, the brain seems to enhance processing of attended messages and suppress processing of unattended messages (Horton et al., 2013) In real-life scenarios, other cues (lip reading) also help us focus on one voice (Golumbic et al., 2013) Focussed Auditory Attention and Hearing Aids People with hearing aids can struggle in cocktail party scenarios, as ‘attended to’ voices are not always enhanced (Geirnaert et al., 2021) EEG can determine which voice a person is attending to. Researchers are now developing ‘neurosteered hearing aids’ that use EEG signals to identify and amplify ‘attended to’ voices In class, I will play a 2 min video explaining this research a little Attention When Viewing Scenes Whilst we can perceive entire scenes, we can only focus attention on one small area of a visual scene at any one moment Our eyes pause on one area (called a fixation), process information, and skip to another (called a saccadic eye movement). This happens 2 - 3 times a sec, helping us to Eye-tracking data from Figure 1 of Henderson (2003). The numbers are quickly process scenes (Henderson, 2003) how many m/s fixations lasted  The Spotlight Theory of Attention Posner et al. (1980) likened visual attention to a fixed-size spotlight that moves around scenes They felt we can only attend to one region of space at a time* and the stimuli on which the spotlight is focused receives priority processing We do perceive information outside the spotlight (peripheral vision), but it receives less processing *Some controversially argue we can focus attention on two or more locations at once (e.g., Awh & Pashler, 2000) The Zoom-Lens Theory of Attention Eriksen and St. James (1986) argued the spotlight is like a camera zoom lens that can be adjusted to alter the visual area it covers (broad or narrow) There is, however, a trade-off between the spotlight’s size and processing efficiency:  Muller et al.’s (2003) participants reacted slower to events when they had a broader Drivers often narrow their focus of attention to focus of attention (relative to a narrower one) focus on potential hazards such as cyclists The Object-Based Attention Theory of Attention Some researchers have questioned whether our spotlight of attention (zoom-lens version of otherwise) is shaped like a circular spotlight. Object-based attention theorists argue the ‘spotlight’ can take the shape of objects of Object-based attention theory suggests the interest, so we process them more effectively. spotlight takes the shape of objects of interest Which theory has the best support? Spotlight vs. Object Based Attention Imagine you have been asked to focus on the centre of the eggs in the fridge (black dot). One of the green or orange symbols will flash, and you must respond as quickly as possible (press a button). Spotlight and object-based attention theories make different predictions about what will happen: Spotlight theory predicts equally fast Object-based attention theory predicts responses to the green and orange symbols faster responses to the green stars Spotlight vs. Object Based Attention Egly et al. (1994) ran a reaction time (RT) study C A analogous to the fridge example on the last page. The goal was to see whether visual attention is like a circular spotlight or object-based. I will now take you through a trial, step-by-step: Step 1: Participants first saw two rectangles D B Spotlight vs. Object Based Attention Step 2: A cue briefly appeared indicating Step 3: A target appeared. Participants had to where a target may soon appear. Participants respond to the target. 75% of the time, it was would attend to that location. The cue below where the cue suggested (e.g., A). When this suggests the target will appear at A happened, response times were fast (324 ms) Target 324 ms Spotlight vs. Object Based Attention What would happen if the cue appeared at A but the target at B or C? Spotlight theory predicts equally fast responses to B and C (they are equidistant from A) Object-based attention theory suggests faster responses to B (it is part of the same object as A) Egly et al. (1994) found faster responses to B, suggesting object-based attention was used  How Prevalent is Object-Based Attention? Subsequent comparisons of spotlight theory and object-based attention theory suggest: 1. Visual attention can be shaped like a spotlight or object-based 2. The default mode is likely ‘spotlight mode’, with object-based attention used less often. Individual differences may exist (see right) Some argue Egly et al.’s task encouraged object-based processing (e.g., the use of cues seems to matter; Donovan et al. 2016) By the end of Attention: Part 1, you should be able to: 1. Explain the difference between focussed and divided attention, and how they are studied 2. Explain how WW2 inspired the creation of the dichotic listening task and how the task works 3. Explain and critically evaluate three models that explain how focussed auditory attention works 4. Explain whether visual attention is like a spotlight, zoom-lens, or if object-based attention occurs