psy 214 lecture # 9 (10/12/2011) – visual attention dr ...rachtma8/psy214/files/ntc09-2.pdf ·...

PSY 214 Lecture # 9 (10/12/2011) – Visual Attention Dr. Achtman

Written by: Erin Carroll, [email protected] of 6

Corrections: • None needed Announcements: • Midterm #2 is 2 weeks from today • Midterm #1 Grades are posted on Moodle Lecture Notes: Outline: -Divided vs. selective attention

-Is attention necessary for perception? -Does attention enhance perception?

-Connection between attention and neural firing Divided Attention: Watching two different things at once -there is evidence that it is too difficult to do, and that we really switch back and forth between multiple things Selective Attention: Paying attention to things of interest and actively suppressing distractors

-What is it?: When we choose to focus on one thing, and to ignore others -Why do we use it?: There is too much going on at any one time to pay attention to everything, the brain would overload. -How is it measured?: Eye-tracking devices, asking questions like, “do you recognize that?”

-What determines where we fixate?: The characteristic of the scene like what is most vibrant

PSY 214 Lecture 9

Topic: Visual Attention Chapter 6, pages 132-152



Ex) Fig 6.1 Eye tracking devices can do tasks like this, showing where a person looks in an order that makes sense for the situation. It makes sense that a person at a baseball game would look to the bases and players, and not out in the distance at the buildings.

-Scene schema: recognizing things because they are out of the ordinary with the scene you are observing.

Ex) Seeing a football player on a baseball field -Stimulus Saliency: how clear/bright an image is determines if it will captivate attention well

Fig 6.5 This figure shows that we are more likely to see the orientation of features, like the clouds and the pointed island because they stand out in the image.

Fig 6.6

This task of making a peanut butter sandwich can measure what the participant is attentive to. The eye tracker device shows what they are looking at. Eye movements always just precede the action, so the experimenter can predict what they will do based on where they look first.

-another example of this is being able to tell where a basketball player will go or throw the ball before they do it based on where they make eye movements to

Is attention necessary? -Yes and No

-Yes, because it is necessary to pay attention if you want to get the details of a topic -No, because you can still get the general gist of an idea without close attention



-Experiment: Fig 6.7 76% of the people who did this experiment could correctly identify there was an animal, even when they had the separate, specific task of identifying if the letters were all the same, or not. But, when there was a face, most could not identify if it was male or female, something that required more detail. Inattentional Blindness -The phenomenon that you cannot perceive things that are obviously able to notice when you are not paying specific attention to it.

-Experiment: Fig 6.9 Subjects were not able to do this task because of Inattentional blindness. If they were warned by being told to “pay attention-something might change”, more people would notice. -There are many examples of Inattentional blindness that we can experience. Here are some links to try out: -http://www.youtube.com/watch?v=vJG698U2Mvo

(This is the experiment done on the basketball court with the gorilla. Many people (46%) do not notice the gorilla walk onto the scene because they are putting their attention on the passes that the white shirted players are making.)

-http://www.youtube.com/watch?v=oQd7rb0wkjY

(This is another fun example, so I won’t spoil it!)

Change Blindness -The inability to detect changes in a scene, even central changes when you’re actively searching

-Ex) 2 pictures flash back and forth, with one thing different between them (see how long it takes to notice the change) Even when you are told to look for the change, you can still miss it. In class we did the airplane example and the Sphinx example. Change Blindness Blindness -Not even being aware of the fact that you are blind to changes Attention does enhance perception:



-But, it can also hinder perception if it is not the right task

-Experiment (Posner, 1980):

There was the simple task of hitting the button when the light went on. It turned out that if the cue pointed in the direction of the light, the subject hit the button faster than if the cue went in the opposite direction of the light. The cues had to be consistent for the experiment to work; if they were random, the subjects would learn to ignore them.

-Experiment (Egly): Fig 6.15

The subjects in this experiment reacted fastest when the cue was at the target. The 2nd fastest was B because it is located in the same object, proving that we group things together if they are in an object, even when C was the same distance from A as B was. -It is easy to see all of the objects of a scene, but confuse the details

-Attention binds features -Ex) See a scene of a man and a woman walking and notice one is wearing a blue coat. Later, you argue that the man was wearing the blue coat, but your friends said it was the woman. The details of the scene were noticed, but confused.

-This is why eye witness testimonies and choosing a criminal from a line-up are problems!

-Any stimulus activates many areas of the brain, different areas for color, motion, location, depth, and form

-Binding combines all of these qualities into one perception -Treisman’s Feature Integration Theory:

- Object Preattentive stage Focused attention stage Perception -concerned with associating features to the objects they belong to

-Treisman and Schmidt’s Illusory conjunction experiment: When multiple objects with many features are present, binding becomes harder



-Balint’s Syndrome: inability to focus attention on a single object

Connection between attention and neuron firing: -Attention enhances the firing of neurons

-demonstrated by many single-unit recording experiments on animals -the effect becomes stronger at higher areas of the visual system, even though it does have a smaller effect in the lower levels (like V1 and striate cortex) -firing is not determined by the image on the retina, but by how significant the image is to the person observing it, according to their behavior

Attention in Autism: -Autistic people pay attention to a talking person by looking at their mouths, while non-autistic people look at their eyes -Non-autistic people look to where another person is pointing, while an autistic person will look somewhere else first and then back and forth -Pelphrey suggested that there is a difference in how Autistic people read others’ intentions compared to non-autistic people

For more information:

• http://www.youtube.com/watch?v=BZ0l9s8_Hmk&feature=related This YouTube video discusses more about change blindness. It shows an interesting experiment done on change blindness as well.

• http://www.pbs.org/wgbh/misunderstoodminds/attention.html This website discusses attention and has an activity about reading with distractions to try that is quick, and interesting!

• http://www.pbs.org/wgbh/nova/body/change-blindness.html This website gives an overview about change blindness and also has a video showing another experiment done on change blindness that is pretty shocking.

• http://www.psychol.cam.ac.uk/lara/projects/vis-percep.html This article is about attention in visual perception of people with Autism since we did not get to discuss it in class.

Real-life examples: • Inattentional blindness is something that probably happens to everyone, many times a day. For

example, the other day I was in such a deep focus on my laptop in Sorelle’s that I didn’t even notice when my friend came and sat down right across from me until she started talking. If you are paying close attention to one specific task, it is easy to not notice otherwise pretty obvious things around you.



• Change blindness is another phenomenon that probably happens more than we even know (as change blindness blindness tells us). An example of this is the ice-breaker game many of us played during freshman orientation where you are facing someone and they change something about their appearance while you close your eyes and then you have to identify what it is they changed. Even though you know they are going to change something, it is often very difficult to point out what that is.

psy 214 lecture # 9 (10/12/2011) – visual attention dr ...rachtma8/psy214/files/ntc09-2.pdf ·...

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