Do the Barn demo. Tell me what has changed between the two images, and about how long it took you to find it.

Psych 463 Sensation & Perception

Dr. Swift

Eighth Assignment (Attention)

1. Motion-Induced Blindness. Go the web-site

http://www.michaelbach.de/ot/mot-mib/index.html

and experience the basic phenomenon.

a. Try to determine what is necessary to get the effect to disappear. You can play with such parameters as stimulus size, pattern contrast (by changing the background and or crosses, dots contrast, speed, etc.

b. Suggest ways of testing out the phenomenon that are not available in the demonstration. (For example, it has been suggested that the complexity of the disappearing stimuli may be relevant. Or, do all the disappearing stimuli have to be the same? Come up with your own—i.e. don’t use these.). Explain why you think your suggestion is a good idea.

2. Change Blindness. Go to http://nivea.psycho.univ-paris5.fr/#CB , scroll down and try out the demos

a. Do the Barn demo. Tell me what has changed between the two images, and about how long it took you to find it.

b. Do the Sailboat demo. Tell me what has changed between the two images, and about how long it took you to find it. (Actually, I have not been able to solve this one, so if you cannot see the change, try to find someone else (outside the class) who can.

c. Do the Gunner demo. Tell me what has changed between the two images, and about how long it took you to find it. Note that this one involves mud splashes to interrupt your attention as opposed to flicker. Tell me which you think was easier, trying if possible to separate out the mud splashes vs. flicker from the ease of detecting the particular change.

d. Also try “The Door Study” at http://www.dansimons.com/videos.html. Why do you think the person was fooled? Do you think you would have been fooled by the switch? Why or why not?

3. Target Detection. Produce stimulus sheets similar to Figure 6.21, reproduced below. (A conjunctive target is one that shares one feature with half of the distractors and another feature with the other half, but is different from all targets. For example, in (b) below there are vertical green bars and horizontal red bars, but only one horizontal green bar. Refer to the text and/or the lecture for a more extensive, but definition of a conjunctive target).  should have one for each of the following (and include them in your assignment submission):

a. Simple target (similar to Figure 6.21a) but with 10 distracters

b. Simple target with 50 distracters

c. Conjunctive (similar to Figure 6.21b) target but with 10 distracters

d. Conjunctive target with 50 distracters

For purposes of comparison, the objects in (a) should be the same as those in (b); the objects in (c) should be the same as those in (d); and the objects in (a) and (b) should be similar to those in (c) and (d). You should have the same target for all 4 cases, making it a simple vs. a conjunctive target based on the distractors you use.

What is your target? ____________________________________________________

Give them to 5 – 10 friends to find the targets. Record and present your results, using a graph (sample spreadsheet, including graph shown at end), plotting time to detect the target as a function of number of distracters for both simple and conjunctive targets. Discuss your results, noting that not only should the complex target take longer, but it should have a steeper slope as well—explain why.

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