I would like you to go to choose one of the three experiments below to do for this assignment. First read through the introduction and the instructions for the online lab experiment.
Week 6: Perceived Depth as a Function of Retinal
Disparity
Random Dot Stereograms (Red/Blue anaglyph glasses required)
16A-Binocular Depth Perception Experiment
Week 7: Global Motion Sensitivity using Random Dot
Cinematography
17A-Motion Discrimination Experiment
Week 8: Visual Search Time as a
Function of Background Distracter Set Size and Type
Visual Search Experiment (01A-Feature
Search; 01B-Conjunction Search)
IMPORTANT: When you click on the button at the bottom of the page to "RUN THE EXPERIMENT" you may be asked to log in. If you log in as GUEST you should be able to get in. You will also need a computer with up to date Java plug-ins.
The experiment takes about 15 minutes - perceptually it seems like forever : -) but don't give up and don't just start clicking on buttons to get it over with because we want the data it provides you when you are done.
After all that, since most of the work was doing the assignment. For this blog post, just say I did the experiment and briefly discuss your experience.Once you are done with your post make list of the terms and terminology you used in your post.
I chose to do the Motion Discription Experiment because I thought that Global Motion Sensitivity was kind of interesting and thought a refresher about Random Dot Cinematography would be beneficial.
For this experiment, the participant watches an 11-frame animation of several dots moving across a small screen. The job of the subject is to select which direction the dots were moving/trending at 12 different levels of percent-correlated-motion (up, down, left, right). Sounds easy enough, and for some the trials it was. There were many trials that even after repeating the stimulus, I still had to guess on which way the dots were trending because it looked like they were all just scattering in different directions.
I found that for many of the trials it was easier to look at the text box to the right of the moving dots screen, and use my peripheral vision to determine which direction the dots were moving.
After completing the experiment it gives you your results with two columns, the Percent Correlated Motion (the 12 levels) and the Percent Correct Discrimination. According to my results, I got 0 correct at the 0 correlated motion level, and did the best (100% correct) at the 48, 54,60, and 66 percent correlated motion levels. I got half correct at the 24 percent correlated motion level. Overall, I was more accurate with the trials at the higher levels of percent correlated motion.
Terms: Motion Discrimination experiment, Global Motion Sensitivity, Random Dot Cinematography, percent correlated motion, percent correct discrimination
I chose to complete the Motion Description Experiment from week 7 because it seemed relevant to the chapter that I just completed. Besides the fact that this experiment was 97 trials of dots flashing in different directions, I found it to be interesting.
The experiment consisted of a quick flash of dots that move in different directions. My task was to determine which direction the dots were moving. I found the first 10 trials to be simple, but I soon began second guessing. I began struggling because I kept thinking that the dots were going the same direction, so I selected 'down' for about 30 trials.
My results say that I got 100% for the percieved correlation of 54, 60, and 66. The other results vary extremely.
Terms: Motion discrimination experiment, percieved correlation.
I chose to do the Motion Description Experiment from Week 7. I found the experiment to be interesting but a bit disorienting and it was starting to give me a headache at the end.
The experiment consisted of 97 trials of dots moving across a screen. My job as the test subject was to guess which direction the dots were traveling. For 0-30 percent of correlated motion I didn't do too well but for 36-66 I got 100% on the correct discrimination, so I was pretty proud of myself for that. But I also had to take some aspirin at the end.
TERMS: Motion description experiement, correlated motion, correct discrimination,
I chose to try out the visual search time as a function of background distractor set size and type experiement. I really enjoyed it and even found it to be a little fun. When I first resd the discription I was a little skeptical of the theory. The more distractors to search through, the more time it would take you to correctly identify the stimulus. I did not buy into it at first because when looking at the examples it seems as if your eyes just quickly jump to the little green circle. While actually doing the experiment on the other hand I was proved wrong, I quickly began to realize that it does take longer based on the number of distractors, except when the little green circle is directly in the center of the screen, I feel like this made it easier to find. This made me think of how we do this in the real world, along the lines of little green circles I thought of green lights while driving and how I it seems like I always pick up on that signal immediatly except today when there was a blue cup in the road that distrated me, just like in the experiment...Fate!
Terms: distractors, stimulus, and visual search time as a function of background distractor size and type experiment.
I ended up doing the Global Motion Sensitivity Experiment from week 7. The experiment involved watching an animation of dots moving across the screen, and you had to guess whether those dots were going right, left, up, or down on the screen. I was able to guess with %100 accuracy on the 36, 42, 48, 54, 60, and 66 percentages of correlation. At the 30% correlation level I guessed right 87.5% of the animations. At the 24% correlations level I guessed right 50% of the time. All lower levels of percent of correlation my percent of correct guess was significantly lower. The correlation percentage had to do with how many of the dots in the animation were moving the same direction. The higher percentage of dots moving in the same direction the easier it was to guess right about if the dots were moving right, left, up, or down. On some of them I really wished there were buttons for right and down, or left and up, and so forth because several of the animations seemed like they were moving in a diagonal direction. It would be interesting to see how the results of our whole class, doing the experiment, compared with one and another. I think they should take out the repeat the stimulus button because it may cause a person to second guess their original thought, which is what the test is trying to measure.
Key Terms: Global Motion Sensitivity, Correlation, Percentage, Animation, Dots
I chose to do the visual search time as a function of background distractor set size and type. The first experiment had you indicating whether a stimulus was present in a set of data. The independent variable was how many distractors were present in the group. The more distractors there were, they theorized it would be harder to find the wanted stimulus. However, my results did not reflect this and were actually opposite of what was expected. The second experiment was the same except the stimulus more closely related to the distractors in color and in shape. I found this to be much more challenging and my results reflected the researchers theory that the more distractors the longer it would take to recognize the stimulus. I do think there was some confounds with the experiment because I am expected to go fast and I know that mistakes won't affect my mean score results at the end.
Terms: distractor, stimulus, independent variable, confounds
The week 7 global motion discrimination sensitivity experiment it what I chose to do also. It was definitely an experience. The experiment was done by using random dot ciematography.
Some of the stimulus were really easy to identify, but some of them I felt like could have gone two ways like down left of down right. Although I am not quite sure all that the results were saying it was obvious to me that higher the percent of correlated motion was the better I was as correctly discriminating.
Key Terms: Global Motion sensitivity, random dot cinematography
I did the experiment for week 7 since that is the week we are on. I found myself having to look at the stimulus more than once when all the dots seemed to be moving in every direction. But once I got above 40 dots moving in one direction I found it easier and easier to (100%) to identify the direction that the dots were moving in. One of the big factors for me was the short time span allowed to view the stimulus in. It made it really hard in some cases to pick a direction.
I did the visual search experiment from week 8. This was broken down into two different experiments. One, the feature search experiment where you were presented with lots of blue X’s and sometimes they would throw in a green O and you were to identify when you were able to see the green O. This was very easy for me. It seemed as if it just jumped right out at you. The second one was the called the Conjunction search. They kept all the blue X’s (like the first experiment) and then they threw in some green Xs. You were then to try to identify when the slide had a Green O on it. This was much harder and took much longer for me to determine than the first experiment.
I did the visual search experiment. The results showed that visual search is a serial process, where you look at every potential object until you find, or don't find, the object. There was a direct relationship between number of distractors and time. Also, there was a relationship of the "object absent" group taking somewhat more time, due to a longer process of looking at all of the objects to determine that there is none; compared to only looking at a few until you find it.
I chose to do the global motion sensitivity using random dot cinematography. In this experiment you have to watch a bunch of dots move across the screen, and then determine what direction the dots were moving. I have to say I didn’t fair to well in this experiment, because half the time I couldn’t tell you what way the dots were going. Staring at the dot basically put me in a trance to the point I couldn’t tell where they were even moving. Overall I noticed as time went on I had a tendency not to be able to decipher what direction they were going. It was kind of an interesting experiment, but after a while it got a little boring.
Terms: global motion sensitivity, and random dot cinematography
I chose to do the global motion discrimination experiment. I chose it because I couldn't really figure out the other two, but I figured any one of them were going to be interesting. This experiment was pretty interesting, in that I felt like almost every dot slide was going down. It wasn't too difficult to differentiate between left and right (i think) than from up and down. Almost every time I thought they were going down. It says I got 100% on the 54 and 66 correlation. I wasn't sure either what the correlations part meant. I wonder if it meant how many dots there were or how fast it was going? Not sure. All interesting, none the less.
The experiment I chose to do was the Visual Search Experiment. There wasn’t a reason why I chose this experiment over the others, but this one was pretty self explanatory, and it wasn’t too time consuming.
This experiment tested your ability of finding a “target” in a set of “distracters.” The experiment tested how quickly you could find the target and how many were answered correct. As the experiment stated usually when there are many background distracters it is harder for you to find the target (it takes more time). This is known as the size effect. On the other hand when there are little or not many background distracters it is easier for you to find the target (it takes less time).
Also in this experiment they measured two types of visual searches that were found and developed by Anne Treisman. These two visual searches are; disjunctive and conjunction. A disjunctive search would be when the target stimulus is different in a salient perceptual level than the distracters, meaning the target could be a different color than the distracters. It has been found that this search is more effective and takes less time, meaning the stimulus is parallel. Treisman states the disjunctive search is a bottom-up perceptual feature because it takes you less time and effort to find the difference. A conjunction search would be when the target and the distracters are similar and they cannot be discriminated from, meaning it is a serial process. A conjunctive search would be harder for someone to find because they are not a bottom-up perceptual feature.
Just as the experiment states it did take me longer to find the target when there were many background distracters, and it was easier for me to find the target when there were little distracters. The experiment measured both disjunctive and conjunction searches and I found in both of these tests it was more difficult to find the target when there were many distracters, and easier when there were less distracters. Also it was much easier for me to finish the second test with little error because the second test measured the disjunctive search (there were green O’s and blue X’s), the target was different than the distracter. My results were more parallel in this test. The first test my results were a bit different. I had many more errors and it took me more time. This was because the first test measured the conjunction search (there were green O’s, green X’s and blue X’s), the target was similar to some of the distracters. For this test my results were more serial. My results matched what was hypothesized by the experiment.
Terms: target, distracters, size effect, disjunctive, conjunction, bottom-up perceptual, parallel, serial
I performed the Week 8 visual search experiment. For some reason, neither of the tests would spit out any results for me after I finished. This was a bit disappointing, so I tried the tests again on a PC to no avail. Though I do not have any hard data on which to base my findings, the reasoning behind the experiment was made very clear. It was pretty obvious that I was spending more time scanning the conjunctive visual fields than disjunctive ones. This relationship also held for fields with more distracters versus those with fewer distracters. As the experimental background states, this is because disjunctive searches allow for simple bottom-up perceptual processing in which the entire field can be scanned at once. This effect can be made slightly more complex with additional distracters, but generally I thought the salient perceptual dimension is so easy to distinguish that this size effect does not matter much.
As for conjunctive searches, this becomes a much more effort-filled venture in which items are scanned one at a time (serially) until one with the features of interest is discovered. The size effect is also much more apparent with conjunctive searches because you must scan for as many items as there are distracters until you happen upon your desired object. The top-down processing involved in conjunctive searching takes a great deal more of your attention, especially in the case of target-absent searches because they cause you to keep scanning longer in order to make doubly sure you did not miss the targeted item.
Terms: conjunctive search, disjunctive search, bottom-up processing, top-down processing, serial, size effect, distracter, target-absent search
I chose to do the experiment on global motion sensitivity using random dot cinematography. This was an interesting thing to perform which would allow me to see how I visualize these random dots moving. The whole idea was to determine which direction (left,right, down, or up) I believed the dots to be moving. According to my results I gradually increased my correct answers after each correlation except 12. 48,54, 60 and 66, which were the last 4 correlations, I received a 100% I did also notice myself replaying certain stimuli, but usually when in doubt I chose the direction of down.
Terms:Global motion sensitivity, random dot cinematography.
For the online class experiment I chose the Global Motion Sensitivity using Random Dot Cinematography. When I started the experiment I didn't think it was that difficult and it seemed like the dots were easy to follow. Soon enough though I was lost in the dots. My eyes could no longer keep up and the dots all looked like they were going both up and down. I received a couple hundred percent on the latter end of the experiment,a lot of 66 percent results in the middle and some lower scores in the beginning. The experiment was interesting but I'm not sure what was being targeted in our visual system. I'm sure we'll elaborate more on the experiments more in class so I'll be looking forward to that.
I chose to do the Motion Description Experiment from Week 7 because it sounded the most interesting to me. At the beginning of the experiment, when I was watching the dots to figure out the direction, I found it to be fun, interesting and exciting however by the end of the experiment, I couldn’t wait to be finished. I was a little dizzy and thankful it was over. I received 100% of correct discriminative however I didn’t do very well at 30% correlation level.
Terms: Motion description, discriminative, correlation.
I can't get in to any of the experiments.
I would send a email to Otto to see if he has any suggestions for you.
Visual Search Time as a Function of Background Distracter Set Size and Type
During the experiment I found it hard to find the green O quickly because my eyes wanted to focus on the bright blue X's . It was interesting that the "distracters" were the color that they wanted us to find. Also, I may have been inattentionally blinded because I was only looking for green O's that I could have perceived and used selective attention.
Terms- distracters, inattentional blindess, selective attention