173 lines
8.4 KiB
Plaintext
173 lines
8.4 KiB
Plaintext
ÜÜÜÜÜÜÜÜÜÜÜÜÜ ÜÜÜ ÜÜÜÜ
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ÜÛÛÛÛÛÛÛÛßÛßßßßßÛÛÜ ÜÜßßßßÜÜÜÜ ÜÛÜ ÜÛÛÛÛÛÛÛÛÜÜÜÜÜÛßß ßÛÛ
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ßÛÛÛÛÛÛÛÛÛÛÛÛÛÛÜ ßÛÛ ÜÛÛÛÜÛÛÜÜÜ ßÛÛÛÛÜ ßÛÛÛÛÛÛÛÜÛÛÜÜÜÛÛÝ Ûß
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ßßßÛÛÛÛÛÛÛÛÛÛÜ ÞÝ ÛÛÛÛÛÛÛÛÛÛÛßßÛÜÞÛÛÛ ÛÛÛÛÛÜ ßßÛÛÛÞß
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Mo.iMP ÜÛÛÜ ßÛÛÛÛÛÛÛÝÛ ÞÛÛÛÛÛÛÛÛÛ ÞÛÛÛÛ ÞÛÛÛÛÛÝ ßÛß
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ÜÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛÝ ÛÛÛ ÛÛÛÛÛÛ
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ÜÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛ ÞÛÛÛÛÛÛÛÛ ß ÞÛÛÛÛÛÛÜ ÜÛ
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ÜÛÛÛÛÛÛÛÝ ÛÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÞÛÛÛÛÛÛÛÛÛß
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ÜÛßÛÛÛÛÛÛ ÜÜ ÛÛÛÛÛÛÛÛÝ ÛÛÞÛÛÛÛÛÝ ÞÛÛÛÛÛÛßß
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ÜÛßÛÛÛÛÛÛÜÛÛÛÛÜÞÛÛÛÛÛÛÛÛ ÞÛ ßÛÛÛÛÛ Ü ÛÝÛÛÛÛÛ Ü
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ÜÛ ÞÛÛÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛ ßÛÜ ßÛÛÛÜÜ ÜÜÛÛÛß ÞÛ ÞÛÛÛÝ ÜÜÛÛ
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ÛÛ ÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛÛÜ ßÛÜ ßßÛÛÛÛÛÛÛÛÛß ÜÜÜß ÛÛÛÛÜÜÜÜÜÜÜÛÛÛÛÛß
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ßÛÜ ÜÛÛÛß ßÛÛÛÛÛÛÛÛÛÛÜ ßßÜÜ ßßÜÛÛßß ßÛÛÜ ßßßÛßÛÛÛÛÛÛÛßß
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ßßßßß ßßÛÛß ßßßßß ßßßßßßßßßßßßß
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ARRoGANT CoURiERS WiTH ESSaYS
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Grade Level: Type of Work Subject/Topic is on:
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[ ]6-8 [ ]Class Notes [Lab: Response Results ]
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[x]9-10 [ ]Cliff Notes [from Stimulus ]
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[ ]11-12 [x]Essay/Report [ ]
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[ ]College [ ]Misc [ ]
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Dizzed: o4/95 # of Words:951 School: ? State: ?
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ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>Chop Here>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ
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Part 1
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In this signal detection experiment, there were 3 parts, each with 50
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trials. On half of the trials, a signal 'x' was presented along with
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visual noise 'z'. The other half of the trials showed only visual noise.
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The task was to locate the signal stimulus 'x' among all other noise
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signals 'z' present. All this was done on a computer generated program.
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Another 2 students' results of the experiment were obtained for
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further analysis of signal detection.
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During the trials there were many 'z' flashing on the screen. The
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objective was to determine if the symbol 'x' was also flashed on the
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screen. The responses to be given were :
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If you are sure you saw 'x' press 5
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If you are fairly sure you saw 'x' press 4
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If you are unsure you saw 'x' press 3
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If you are fairly sure you didn't see 'x' press 2
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If you are sure you didn't see 'x' press 1
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The dependent variable in this experiment was the response in
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pressing 1,2,3,4 or 5. The independent variable was the signal stimulus
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'x' which flashed across the screen.
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The design of this experiment is the within-subject design since the
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conditions were randomized from trial to trial and students were tested
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under mainly the same experimental conditions.
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The Questions which can be addressed with this design are how would
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the results have changed if the design had been a between- subject design?
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Also what would happen if the trials were not randomized? How would this
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factor distort the results in this within-subject design.
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Part 2
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Results
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Group 1
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Condition 1 Condition 2 Condition 3
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0.01 sec. 0.05 sec. 0.1 sec.
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1+2+3+4+5 5
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1+2+3+4+5 5
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1+2+3+4+5 5
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Signal 20 13 29
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29 25 24
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Noise 30 0 21
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2 25 1
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P(Resp +/S) 0.6875 1 1
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P(Resp +/N) 0 0.952 3.846
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D' -4.7652 -1.374 -1.797
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Group 2
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Condition 1 Condition 2 Condition 3
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0.01 sec. 0.05 sec. 0.1 sec.
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1+2+3+4+5 5
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1+2+3+4+5 5
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1+2+3+4+5 5
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Signal 25 7 25
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24 25 24
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Noise 25 0 25
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6 25 1
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P(Resp +/S) 0.68 0.96 0.96
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P(Resp +/N) 0 0.24 0.04
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D' -4.794 -0.857 -1.752
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Group 3
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Condition 1 Condition 2 Condition 3
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0.01 sec. 0.05 sec. 0.1 sec.
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1+2+3+4+5 5
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1+2+3+4+5 5
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1+2+3+4+5 5
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Signal 18 13 5
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20 4 25
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Noise 19 0 25
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0 20 0
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P(Resp +/S) 0.419 0.84 0.862
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P(Resp +/N) 0 0 0
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D' -4.491 -4.933 -1.602
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In group 1, the probability of the response signal stimulus 'x' was
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the greatest in condition 2 and condition 3 where it was 1. The
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probability of a noise signal was lowest in condition 1 where it was zero.
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The distance between the means of the two distributions was closest in
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condition 2. The value for D' in condition 2 was -1.374. So overall in
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group 1, the best response for the signal stimulus is shown in condition 2,
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where the stimulus flash duration was 0.05 seconds.
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In group 2, the probability of the response signal stimulus was
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greatest in condition 2, with 0.96. The lowest probability of a noise
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response was in condition 1, with the result of 0. The closest distribution
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of the 2 means was in condition 2 with -0.857.
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The best response to the signal stimulus 'x' was again in condition 2
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with a stimulus flash duration of 0.05 seconds.
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In group 3, the highest probability of a response signal being a 'hit'
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was in condition 3, which was 0.862. The lowest probability for a false
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alarm was in all 3 conditions which equalled 0. The distance between the
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means of the two distributions was the lowest in group 3. Therefore in
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group 3 the best condition for responding to a hit was in condition 3,
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which had a stimulus flash duration of 0.1 seconds.
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Signal detection approaches provide ways of examining sensory factors
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and response bias. A hit rate in signal detection gives us an estimate of
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the subjects sensitivity. The higher the hit rate is, the more sensitive
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the subject. Also the higher the false alarm rate, the less the subject
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is going to respond with a hit rate. In responding to the stimuli the
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subject will either sense or not sense the stimuli, and in addition will
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also decide what to report. So because the subject decides what to report
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this is why all three groups had quite different results.
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Part 3
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Two other variables that could influence the sensitivity dimension of
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the subjects response are:
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1) The number of choices to be made if the signal stimulus was present.
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Five choices are too many (1,2,3,4,5). It would have been better if there
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were only three choices : sure you saw 'x', unsure, and sure you didn't see
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'x'.
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2) The time when the signal stimulus appeared on the screen. If it was
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the first or last signal shown, 'x' could be identified very easily.
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Another variable that may influence the response-criterion dimension
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of the subjects response was how dispersed the signals were on the screen.
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Sometimes they were bunched together and so it was easier to locate 'x'.
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But if the signals were all spread out across the screen then it was harder
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to locate the signal stimulus.
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A confounding variable in this signal detection experiment could be
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how you were positioned in your distance from the computer screen. If you
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were not positioned a constant distant away from the screen, this would
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affect how you saw the signals. If the signals were spread out and you
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were very close to the screen then you would not be able to clearly
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recognize the signal stimulus 'x' among all the other noise signals 'z'.
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