PSYC 230 Chapter 4

The Binding Problem

how features are linked together so that we see unified objects in our visual world rather than free-floating or miscombined features Sometimes people make errors ------Especially when task is difficult, or distracted by a secondary task

The main difference between early and late selection models of attention is that in late selection models, selection of stimuli for final processing doesn't occur until the information is analyzed for A. modality B. location C. meaning D. physical characteristics

meaning

Filter (in Broadbent's Filter Model)

Identifies attended message based on physical characteristics Only attended message is passed on to the next stage (Detector)

Change blindness

Inability to detect changes in scenes you are looking at Typically uses a flicker paradigm that prevents the actual change from being observed ------Glancing away from road while driving; can be difficult to spot changes If shown two versions of a picture, differences between them are not immediately apparent ------Task to identify differences requires concentrated attention and search, several flickers back and forth With limited pool of resources, we simply cannot fully process all information in our environment

Focused attention stage (feature integration theory)

Individual and independent features are combined to form objects Attention is necessary at this stage Then, see the objects as "whole"

Treisman's Attenuation Model

Intermediate-selection model Attended message can be separated from unattended message early in information-processing system (physical characteristics, language, and meaning) Selection can also occur later Known as a "leaky filter" model since some information still gets through Main point: Leaky filter model All information processed to some degree But not all activates a representation The attended message, and parts of the unattended, gets through to memory

Deutsch & Deutsch, 1963

Late selection model Selection of stimuli for final processing does not occur until after all information has been analyzed for meaning Evidence from MacKay (1973) experiment

MacKay, 1973

Late selection model experiment Attended ear: Ambiguous sentences presented & shadowed ------"They were throwing stones at the bank" Unattended ear: Biasing word presented either ------"River" or "Money" At test, choose which sentence was closest in meaning to original attended message ------They threw stones toward the side of the river yesterday ------They threw stones at the savings & loan association yesterday The meaning of the biasing word influenced participants' choices Participants were unaware of the presentation of them This is unexplained by Treisman's model: meaning shouldn't get through

Perceptual Load and the Load Theory of Attention

Low-load task ------Few resources used, able to process other information ------Walking as an adult ------Driving at 22 High-load task ------Many resources used, difficult to process other information ------Walking as a toddler ------Driving at 16

Short term memory (in Broadbent's Filter Model)

Receives output of detector Holds information for 10-15 seconds May then transfer it to long-term memory

Overt Attention

Shifting attention with eye movements Saccades: rapid, jerky movements of the eyes from one place to another Fixations: short pauses on points of interest 3-5 saccades per second! Scanning is necessary because good detail vision occurs only for things you are looking at directly

Specificity of Resources

Similar tasks will compete for similar resources, diminishing performance EXAMPLES: Listening to light instrumental music while sending an email ------Typically not too difficult ------Task B (listening to music) makes use of mental resources not needed for task A (reading or writing) Talking with a colleague while writing ------More conflict over mental resources ------Task B requires constructing and communicating meaning in sentences, just like task A does

Dear Aunt Jane experiment

Subjects heard "Dear 7 Jane" and "9 Aunt 6" in separate ears but reported hearing "Dear Aunt Jane" from their attended ear Challenges Broadbent's Filter Model

According to Treisman's feature integration theory, the first stage of perception is called the ________ stage. A. feature analysis B. focused attention C. preattentive D. letter analysis

preattentive

Saccades

rapid, jerky movements of the eyes from one place to another

Fixations

short pauses on points of interest

What happens when we selectively attend?

1) Unattended stimuli are largely ignored 2) But some unattended information is still processed

Illusory conjunctions

A situation, demonstrated in experiments by Anne Treisman, in which features from different objects are inappropriately combined. Why? ------Features are initially "free floating" and not bound to a stimulus

Feature Integration Theory

An approach to object perception, developed by Anne Treisman, that proposes a sequence of stages in which features are first analyzed and then combined to result in perception of an object.

Attenuator (in Treisman's Attenuation Model)

Analyzes incoming messages in terms of (1) physical characteristics, (2) language, and (3) meaning Attended message is let through at full strength Unattended message is let through at weaker strength

Covert Attention

Attending to something without moving eyes to it During reading we process words in the fovea but we also process words that we are not fixating directly and which fall in our parafovea. In the latter case we are shifting attention covertly to the next word to be read. Precueing: directing attention without moving the eyes ------Participants respond faster to a target at an expected location than at an unexpected location ------Even when eyes kept fixed!

Bottom-up determinants of attention:

Attention can be captured automatically by a stimulus Based primarily on physical characteristics of the stimulus (not meaning) ------Color, motion, contrast, etc. Stimulus salience ------Areas that stand out and capture attention ------Can define saliency maps: areas of an image that are more likely to be attended to based on perceptual characteristics like hue, contrast, orientation and intensity

Physiology of Attention

Attention enhances neural responding ------Essentially, attention is the enhancement of processing certain aspects of the environment ------Remember the example of reading (overt attention) Attentional processing is distributed across a large number of areas in the brain (surprise!) ------There is no location of attention ------Enhanced neural responding can occur at any location of the brain responsible for "that" type of processing

Dictionary unit (in Treisman's Attenuation Model)

Contains words, each having threshold for being activated Words that are common/important have low thresholds Words that are uncommon have high thresholds

Precueing

Directing attention without moving the eyes Participants respond faster to a light at an expected location than at an unexpected location Even when eyes kept fixed

Broadbent's Filter Model

Early selection model ------Because attended information is "selected" early The filter selects relevant information based on physical characteristics and passes it on to the detector which processes it and extracts meaning and sends it to short term (working) memory Filters out information before it is analyzed for meaning ------Also called a bottleneck model ------Only lets some information through Can't explain the Stroop Effect, Dear Aunt Jane experiment

Models of Selective Attention

Early selection model ------Broadbent's (1958) filter model (Bottleneck model) Intermediate selection model ------Treisman's (1964) attenuation model (Leaky filter model) Late selection models ------Deutsch & Deutsch (1963), MacKay (1973)

Treisman and Schmidt (1982)

Evidence for a Preattentive Stage: ------Screen flashed briefly (1/5th of a second) ------Task: Report the numbers and then the shapes at each location ------Evidence for illusory conjunctions ------Participants mistakenly combined features of different shapes 18% of the time ------Saying "small red circle" and "small green triangle" Evidence for a Focused Attention Stage: ------Identical to prior experiment, but now ignore black numbers and just focus on objects ------No evidence for illusory conjunctions ------Participants can correctlypair shapes and colors

Stroop Effect

Explains the decreased speed of naming the color of ink used to print words when the color of ink and the word itself are of different colors

Forster and Lavie (2008) Assessing Load

High-load condition: Distractor has minimal affect on reaction time ------Participants are already using lots of resources ------Not many left over to process distractor Low-load condition: Distractor affects reaction time to greater degree ------Participants aren't already using many resources ------Have left over to process distractor ------Attentional capture Can be explained by load theory of attention With the low-load task, there is still processing capacity left ------Resources are still available to process the task-irrelevant stimuli, slows down responding time ------Stroop effect With high-load task, all of processing capacity is being used, no resources left to process other stimuli ------Less likely to be distracted!

Effects of Load on Selective Attention

High-load experiments support early-selection models of attention ------Not much information gets through ------Extraneous information does not influence performance Low-load experiments support late-selection models of attention ------Extra information does get through ------Has a much stronger influence on performance

Sensory memory (in Broadbent's Filter Model)

Holds all incoming information for a fraction of a second Transfers all information to next stage (Filter)

Inattentional blindness

Not attending to something that is clearly visible, and failing to notice it Can happen even when directly looking at it ------Open the fridge and can't find what you're looking for when it is right there ------Look at the display in a department store window, fail to notice the reflections on the window's surface ------Shift attention to the reflections, less aware of display Our processing capacity is occupied by a task, and we are impaired at noticing other stimuli

Preattentive stage (feature integration theory)

Objects analyzed into separate features (separate areas of brain) Occurs very early in the perceptual process Is automatic, effortless Happens outside of conscious awareness

Balint's Syndrome

Patient R.M. had disorder known as Balint's syndrome Inability to focus attention on individual objects Difficulty fixating eyes Had difficulty with conjunctive searches Demonstrated illusory conjunctions even when presented with stimuli for 10 seconds!

Detector (in Broadbent's Filter Model)

Processes all information of attended message to determine higher-level characteristics of the message

Selective Attention

The ability to focus on specific stimuli, locations, or messages while ignoring other information We do not attend to a large fraction of the information in the environment We filter out some information and promote other information for further processing

Processing Capacity

The amount of information a person can handle at any given moment Sets a limit on their ability to process incoming info

Perceptual Load

The difficulty of a task High-load vs. Low-load

Divided attention

The distribution of attention among two or more tasks ------Performing multiple tasks simultaneously ------Depends on a number of factors: practice, task difficulty ------Only possible when the sum of the tasks' demands is within the "cognitive budget"

Binding

The process by which features such as color, form, motion, and location are combined to create our perception of a coherent object

Attention

The process of focusing on specific features of the environment or on certain thoughts or activities ------Selective: We attend to one thing while ignoring others ------Limited: In capacity and timing ------Distraction: one stimulus can interfere with the processing of another ------Can be used overtly or covertly: with our without eye movements ------Voluntary or Involuntary -consciously attend to information, or have information "grab" (capture) our attention ------Can be divided: Paying attention to more than one thing at once

Dichotic Listening (Cherry, 1953)

Using headphones, a person listens to two different messages, one presented to each ear Instructed to pay attention to message in one ear (the attended message) and repeat it out loud while ignoring the message in the other ear (the unattended message) ------Process called "shadowing" Participants could not report the content of the message in the unattended ear ------Even occurs when a word gets repeated 35 times! (Moray, 1959) ------Knew that there was a message But the unattended ear is being processed at some level... ------Gender and tone are sometimes noticed

Top-down determinants of attention:

Voluntarily shift attention to new target Scene schemas ------Knowledge about what is contained in typical scenes ------Help guide fixations from one area of a scene to another Eye movements are determined by task demands ------Eyes movements precede motor actions by a fraction of a second

Parafovea

area around the fovea where images can still be perceived but at a lower resolution (peripheral vision)

Fovea

central area of the retina with higher resolution. Images that fall within the fovea are seen with more clarity and better detail (central vision)

Difficulty in recognizing an alteration - even a very obvious one - in a scene is called _______ blindness. A. covert B. exogenous C. endogenous D. change

change

Illusory conjunctions are A. misidentified objects using the context of the scene. B. combinations of features from different stimuli. C. features that are consistent across different stimuli. D. combinations of features from the masking field and the stimuli.

combinations of features from different stimuli.

The distribution of attention among two or more tasks is known as A. dual attention B. divergent tasking C. selective attention D. divided attention

divided attention

A bottom-up process is involved in fixating on an area of a scene that A. fits with the observer's interest B. carries meaning for the observer C. is familiar D. has high stimulus salience

has high stimulus salience

Strayer and Johnston's (2001) experiment involving simulated driving and the use of hands-free vs. handheld cell phones found that A. talking on either kind of phone impairs driving performance significantly and to the same extent. B. driving performance was impaired only with the handheld cell phones. C. driving performance was impaired less with the hands-free phones than with the handheld phones. D. divided attention (driving and talking on the phone) did not affect performance

talking on either kind of phone impairs driving performance significantly and to the same extent.

Automatic processing occurs when A. cognitive resources are high B. response times are long C. tasks are well-practiced D. attention is focused

tasks are well-practiced