L2 - Perception & Attention PDF

SS3712 – COGNITIVE PSYCHOLOGY L2 –PERCEPTION & ATTENTION GILBERT LAU WHAT DO YOU SEE PERCEPTION  Experiences resulting from stimulation of senses  Somehow our brains automatically process these information  Extremely difficult to do yet our brains are extremely quick and efficient in doing s...

SS3712 – COGNITIVE PSYCHOLOGY L2 –PERCEPTION & ATTENTION GILBERT LAU WHAT DO YOU SEE PERCEPTION  Experiences resulting from stimulation of senses  Somehow our brains automatically process these information  Extremely difficult to do yet our brains are extremely quick and efficient in doing so WHAT MAKES PERCEPTION PROCESS DIFFICULT  The Inverse Projection Problem WHAT MAKES PERCEPTION PROCESS DIFFICULT  Identifying hidden or blurred objects WHAT MAKES PERCEPTION PROCESS DIFFICULT  Items look different from different viewpoints WHAT MAKES PERCEPTION PROCESS DIFFICULT  Scenes contain high-level information COMPUTER-VISION SYSTEMS  Used to be bad at perceiving objects until recent years  But still, humans perform better at this task MECHANICS OF PERCEPTION  Bottom-up processing  Information originating from the environment → creating an image on the retina  Top-down processing  Information originating from the brain → enabling people to rapidly identifying objects and scenes PERCEPTION IN SPEECH  Speech are sound signals  Continuous sound enter the ears and triggers signals that are sent to speech areas of the brain (bottom-up)  If the listener understands the language, their knowledge forms perceptions of individual words (top-down) HOW WE IDENTIFY WORDS  Speech segmentation  Depends on how familiar you are with the language  We are able tell when a word starts and ends within a sentence  Transitional probabilities  The likelihood of one sound will follow another within a word  Learned by infants through “statistical learning”  Example: Pretty Baby are two words, because the probability of the sound “tty” is followed by “ba” is extremely low PERCEPTION OF OBJECTS  Helmholtz’s Theory of Unconscious Inference  We make unconscious inferences about the environment  Based on the likelihood principle  “It is likely that the Blue rectangle is in front of the red rectangle” NOT “It is a blue rectangle in front of a red odd-shaped object” GESTALT PRINCIPLES OF PERCEPTUAL ORGANIZATION  Describe the following GESTALT PRINCIPLES OF PERCEPTUAL ORGANIZATION  Originated with Wundt’s structuralism  Our experience could be understood by combining elements of sensation  Gestalt psychologists  Did not agree it was merely ‘adding sensations’  Wertheimer  Illusion of movement (“Apparent Movement”)  Movement is perceived when nothing is actually moving  “The whole is different from the sum of its parts” GESTALT’S PRINCIPLES OF PERCEPTUAL ORGANIZATION Pragnanz (i.e. Simplest form) WORKSHEET EXERCISE Group 1 Group 2 REGULARITIES OF ENVIRONMENT  Our brains take frequently occurring characteristics (“regularities”) into account Physical regularities  Leads to the Oblique effect Better at recognizing things in vertical or horizontal orientations because it is natural for things to either be vertical or horizontal  Objects can overlap another  Light-from-above assumption We perceive them differently because we ‘assume’ light comes from above ACTIVITY  Close your eyes and visualize REGULARITIES OF ENVIRONMENT  Our brains take frequently occurring characteristics (“regularities”) into account Semantic regularities  When perceiving objects, our brain considers the scene it is in by drawing information from “scene schemas”  a representation of what a particular scene looks like BAYESIAN INFERENCES  Determine based on prior probability and likelihood  Example BAYESIAN INFERENCES  Based on experience, you know a book is rectangular in shape  Combined with your perception of the object’s distance and angle, you concluded that the likelihood of “the object is a book” is high  All these ‘calculations’ are automatic in your head COMPARING THE PRINCIPLES  Helmholtz, Regularities of Environment, & Bayesian inferences  Emphasize on data about the environment  Relies on prior experiences  Gestalt  Emphasizes on the way the brain organizes information  Naturally built-in PERCEPTION INTERACTING WITH ACTION  Movement facilitates perception of objects  Reveals more information  Provides a different viewpoint or perspective  Movement coordinates between perceiving stimuli and taking action Notice (again) how quick your brain works, everything is done automatically HOW THE BRAIN COORDINATES THE PERCEPTION AND ACTION?  Our brain processes information via the Ventral pathway and the Dorsal pathway  The Ventral pathway  Ventral means the front part of anatomy  Processes what the object is  Sometimes called the Perception pathway  The Dorsal pathway  Dorsal means the back part of anatomy  Processes where the object is  Sometimes called the Action pathway BRAIN ABLATION EXPERIMENT  Underleider & Mishkin (1982)  Remove parts of the brain and see if a monkey can compete two tasks  Food is hidden underneath the ‘covers’  Object Discrimination Problem  Remove the triangular cover  Landmark Discrimination Problem  Remove the cover closer to the cylinder BRAIN ABLATION EXPERIMENT  When the temporal lobe is removed, the monkey fails the object discrimination problem (the what pathway disrupted)  When the parietal lobe is removed, the monkey fails the landmark discrimination problem (the where pathway disrupted) D.F. MAILING TASK  Milner & Goodale (1995)  D.F. suffered damage in temporal lobe (parietal lobe is in-tact)  Fail when asked to “match orientation” (Perception pathway)  Success when asked to “Mail” the card (Action pathway) MIRROR NEURON SYSTEM  Similar neuron firing patterns when you watch someone perform an action, AND when you do the same action yourself  “Mirrors” the action in the brain  What’s the purpose  Researchers are not sure!  Some suggest it is for determining the goal or intention behind an action  Some suggest it is the expectation of what the next “most likely” action is BREAK QUESTION DIFFERENT ASPECTS OF ATTENTION  Selective attention  Attending to one thing while ignoring others  Distraction  One stimulus interfering with the processing of another stimulus  Divided attention  Paying attention to more than one thing at a time  Attentional capture  Rapid shifting of attention EARLY SELECTION MODELS  Models that emphasizes the selection of information early on in the process  Broadbent’s filter model of attention  Triesman’s attenuation model of attention BROADBENT’S FILTER MODEL OF ATTENTION  There is a filter that blocks out the less relevant sensory stimuli  Only let the information you are attended to pass through  Explains the cocktail party effect  You can always hear people call out your name in a loud and noisy part The filter identifies the message that is being attended to based on physical characteristics (tone of voice, pitch, speed of talking, accent, etc.) DEMONSTRATION: DICHOTIC LISTENING TEST  Play different messages on each ear  Asked the participant to focus attention on one side  Repeat the words (“shadowing”)  Findings  Can’t report what they heard in the unattended ear  Can tell whether it was spoken by male or female IF BROADBENT’S MODEL WERE TRUE…  All unattended messages should be filtered out  There should be no information passed through to short term memory “DEAR AUNT JANE” EXPERIMENT (GRAY & WEDDERBURN, 1960)  If shadowing works, the person should hear “Dear 7 Jane” instead of “Dear Aunt Jane” TRIESMAN’S ATTENUATION MODEL OF ATTENTION  Suggests both language and meaning can be used to separate messages  Messages are processed based on  Physical characteristics  Language  Meaning  Final output is determined by a dictionary unit Unattended messages are still present but are weaker than the attended message LATE SELECTION MODELS  Most information are processed to the level of meaning before message to be further processed is selected  “They were throwing stones at the bank”  Without processing the meaning of the first part of the sentence, how do you know whether the word “bank” meant a river or money? Early / Late selection can be demonstrated under different conditions Suggests there are different factors that control attention LOAD THEORY OF ATTENTION  Two factors affect our ability to ignore distracting stimuli  Processing capacity (amount can handle)  Perceptual load (difficult)  Low-load tasks only use up small amount of processing capacity  Difficult tasks that may require practice are high-load tasks, requires more processing capacity THE STROOP EFFECT  Delay or increase in reaction time due to inability to ignore a task-irrelevant stimuli  Task-irrelevant stimuli draws away your attention or increase your cognitive load  Sometimes called the congruency effect DIRECTING VISUAL ATTENTION  Where’s Wally / Where’s Waldo?  Where do we usually look?  How do we determine where to look? SCANNING BASED ON EYE MOVEMENT  Central & Peripheral vision  Fixation  The focus point your eyes are looking at  Saccadic eye movement  Rapid, jerky eye movement from one fixation to the next  Overt attention  Shifting of attention from one to another by moving the eyes  Opposite of Covert attention, shifting of attention while fixated SCANNING BASED ON STIMULUS SALIENCE  Our attention is drawn by a physical property of stimulus because it has huge contrast  https://www.youtube.com/watch?v=YgJ5ZEn67tk SCANNING BASED ON COGNITIVE FACTORS  Our attention is drawn by things that did not make sense in a scene according to our scene schema SCANNING BASED ON TASK DEMANDS  Often times our attention is based on the task we’re doing (current) or needs to be done (prediction) ATTENTION IMPROVES OUR ABILITY TO RESPOND TO A LOCATION  PsychoPy Exercise: Precueing (Posner et al., 1978) ATTENTION IMPROVES OUR ABILITY TO RESPOND TO A LOCATION WHAT IF WE CHANGE UP THE LOCATIONS OF THE TARGET  Two orange rectangles will be presented  Why B quicker than C?  Cue at A, Targets can be A/B/C/D  Because the attention at A was spread throughout the object (orange rectangle) OTHER EFFECTS OF ATTENTION  Improves response to objects  Affects perception  Things we attend to are more richly colored and have better contrast than non-attended objects  Affects physiological response ATTENTIONAL WARPING  Map of categories on the brain changes so more space is allotted to categories that are being search for DIVIDED ATTENTION  Can we attend to more than one thing at a time? CHALLENGE FOR YOU!  Build this experiment in PsychoPy Use a new target for each trial This is one trial On half of the trials (20 frames), one of the frames contained the target stimulus RESULTS Training will increase performance but only to a certain extent DIVIDED ATTENTION  Can be trained IF the task becomes automatic processing  Driving  Locking the door when you leave the house  BUT it still takes away some of your attention capacity, just much less  The harder the tasks, the more difficult it becomes (require higher-load) DISTRACTIONS IN REAL LIFE  Direct our attention away from something we are doing  Examples: Cell phones while driving, internet & social media while studying  Operant conditioning (Checking our phones for messages)  We checking our phones all the time  We don’t ALWAYS have a message but we check it anyway, why?  Variable reinforcement  When there IS a message, it acts as a rewards and reinforces your checking behavior DISTRACTIONS CAUSED BY MIND WANDERING  Mind wandering (or daydreaming)  Distracted by other thoughts that appear in your head and forgot what you were doing  Examples: Mindless reading, zoned-out during a conversation  Possibly associated with the Default Mode Network being activated INATTENTION  When we don’t pay attention to specific information, we may miss things that are right in front of us  Inattentional Blindness  https://www.youtube.com/watch?v=iiEzf3J4iFk  Inattentional Deafness  So attentive to another task that we were not aware of hearing a sound stimuli CHANGE DETECTION  Pay attention to the photo on the right  Tell me what changed CHANGE DETECTION  Change Blindness  https://www.youtube.com/watch?v=vBPG_OBgTWg  https://www.youtube.com/watch?v=cW8UiTQtiwA  Continuity errors in movies  https://www.youtube.com/watch?v=ATy-sltLicw HOW ATTENTION AFFECTS OUR LIVES  Brings things to our awareness and enhance our ability to perceive and respond  Binds (Integrates) features to create perception of a coherent object  Feature Integration Theory  Object processing first goes through preattentive stage  Stimulus is broken down into features, usually automatic, unconscious, and effortless  Information is moved to the focused attention stage  With attention, it combines features such that the observer is consciously aware of the object DEMONSTRATION: ILLUSORY CONJUNCTIONS (TREISMAN & SCHMIDT, 1982) FOCUS ON THE NUMBERS: Shape Shape Number Number Shape Shape 8 WRITE DOWN THE NUMBERS YOU SEE? DRAW THE SHAPES YOU SAW (LABEL THE COLORS) 3 REVEAL 8 3 ILLUSORY CONJUNCTIONS  Features are “freely floating” in your head  Your mind combines features from different stimuli  Can occur even if the stimuli differ greatly in shape and size BALINT’S SYNDROME  Patient R.M. is a patient that has damage in the parietal lobe  Caused an inability to focus attention on individual objects  Lack focused attention made it extremely difficult to combine features correctly  Example  When presented with a red T and blue O, sometimes he’ll respond there’s a blue T CONJUNCTION SEARCH EXPERIMENT – FIND THE HORIZONTAL GREEN LINE TRY AGAIN FEATURE SEARCH VS CONJUNCTION SEARCHES  Feature search  Only targeting a single feature  Conjunction search  Targets a combination of features  Could be two or more features  People with Balint syndrome are bad at doing conjunction searches ATTENTIONAL NETWORKS  Similar to perception, the brain seems to allocate attention two ways  Ventral attention network  Based on stimulus salience (physical properties)  Dorsal attention network  Top-down process (scene schemas, task based) SYNCHRONIZATION OF PATHWAYS  The brain has to connect the information processed from different pathways for us to function effectively  Executive function network  Involves two separate network  Responsible for executive function, such as cognitive control, inhibitory control, decision making, planning, etc.