恒常刺激法测音高阈限

1、Experime nt ReportName:曾翘楚 Zoe Major:Psychology No: 2012213970 Report time: 2013/12/25The method of constant stimuli1 In troducti on1.1 Experime nt objectiveHave a good grasp of the method of con sta nt stimuli and measure the differe nee threshold of pitch.1.2 Experiment contentLearn the method of

2、constant stimuli. Do the experiment of measuring difference threshold of pitch and collect data the n an alysis it.Difference threshold of three kinds of reacti on:Up differe nce threshold (Dlu) = up- equalLower differe nce threshold (Dli) =equal- lowerDiffere nce threshold= (Dlu+Dli)/21.3 Experimen

3、t meaningMethod of con sta nt stimuli is one of the importa nt ways in classical psychological physics. The characteristic of the method of constant stimuli is a few stimulates, including 5 to 10, which is unchangeable in the whole procedure of measure. Every time a paired of stimulates are displaye

4、d, participa nts are required to compare the two stimuli and make a decisi on.When using the method of con sta nt stimuli to measure the differe nce threshold, participa nts are recomme nded to respond that whether the second stimulus is same to the first one, stronger or weaker than the first stimu

5、li. In this way, we can get two turning points of feeli ngs. Further the n, we can get up-threshold and lower-threshold.2 Method2.1 Subject4 college stude nts of CCNU. They are all females whose ages are range 18 to 20.2.2 Equipment or materialPsykey experiment system and computers. A series of pitc

6、h including 7 pitch materials in different rate (691694697700703706709 or 688692698700704708712). A keyboard con tai ns a red bottom, a green bottom and a yellow bottom.2.3 procedureBefore the formal experiment, we should do a prepare experiment in the method of minimal difference to measure a gen e

7、ral threshold. Accord ing to the results of prepare experime nt, we should choose differe nt series of pitch.In prepare test, the initial difference rate of pitch is 3Hz. Firstly, participants are required to compare a standard stimuli and the minimal or biggest stimuli. Each group contains ten time

8、s comparison for a pair of stimuli. If both of two groups ' accuracies are high than 90%, we will choose the group whose interval is 2Hz; and if the accuracy is less tha n 70%, the group of 2Hz in terval should be chose n. Or else, we will use 3Hz in terval.The specific method of operati on is b

9、elow:After two pitch displayed in order, if participants think the second pitch is same to the first one, he or she should press yellow bottom. And if they think the second one is higher than the first one, they should press the red bottom or else press ing gree n bottom is correct react ion. After

10、them mak ing a decisi on, ano ther pair of pitch would be displayed.After prepare experime nt, we will en ter into main experime nt.In formal experiment, the operation is same to the prepare experiment. There are 7 changeable stimuli including one standard stimulate. Each pair of stimulate should be

11、 displayed randomly and compared for ten times and 70 times in total.When finished experiment, computers would record the date. Finally, we should collect data and analysis it.3 ResultsI picked up 4 participants ' data to analysis. The specific results are below:Participa nt 1:Chan geable stimul

12、iThe n umber of judgme nt(-)1 (=)(+ )(+ ) + (=)69190.00%10.00%0.00%10.00%69470.00%30.00%0.00%30.00%69730.00%70.00%0.00%70.00%7000.00%90.00%10.00%100.00%7030.00%60.00%40.00%100.00%7060.00%60.00%40.00%100.00%7090.00%20.00%80.00%100.00%This is the first participa nt result. Accords ng to de graph, we c

13、an inform that both of her Dlu and Dli is n early 0, we can reas on able predict that her differe nee threshold is n early 0. She is very sen sible to the differe nee of pitch.Participa nt 2:Chan geable stimuliThe nu mber of judgme nt(-)1 (=)(+ )(+ ) + (=)68870.00%20.00%10.00%30.00%69250.00%30.00%20

14、.00%50.00%6960.00%80.00%20.00%100.00%70020.00%60.00%20.00%80.00%70430.00%50.00%20.00%70.00%7080.00%20.00%80.00%100.00%7120.00%0.00%100.00%100.00%Her data and picture reveal that her Dlu=2 and her Dli=3, in that case, her differe nee threshold is 2.5.Participa nt 3:Chan geable stimuliThe nu mber of j

15、udgme nt(-)1 ( = ) 1(+ )(+ ) + (=)68870.00%30.00%0.00%30.00%69240.00%60.00%0.00%60.00%69610.00%90.00%0.00%90.00%7000.00%100.00%0.00%100.00%7040.00%90.00%10.00%100.00%7080.00%50.00%50.00%100.00%7120.00%20.00%80.00%100.00%The data and graph ack no wledge us that both of her Dlu and Dli is n early 0, w

16、e can reas on able predict that her differe nee threshold is n early 0. She is very sen sible to the differe nee of pitch.Participa nt 4:The nu mber of judgme ntIdl lyuduiu bUIIIUII(-)(=)(+ )1 ( + ) + (=)68860.00%20.00%20.00%40.00%69280.00%10.00%10.00%20.00%69640.00%40.00%20.00%60.00%70020.00%70.00%

17、10.00%80.00%70440.00%30.00%30.00%60.00%70810.00%20.00%70.00%90.00%71210.00%0.00%90.00%90.00%Her data and graph suggest that her Dlu is approximately equal to 2.5 and her Dli is approximately equal to 4.5, in that case, her differe nee threshold is n early 3.5.4 Diseussi on4.1 Differenee threshold of

18、 75%When using method of con sta nt stimuli, we usually ask partieipa nt to resp onse stron ger/weaker or equal. I n that ease, we can gain two turn points of feeli ng in a series of reaeti on, and accord ing to these we can know the up threshold and lower threshold. While some times, partieipants a

19、re only required to response whether the changeable stimuli is stronger or weaker than the standard stimuli. This method can overcome the flaws of differe nee error in flue need by degree of con fide nee in three kinds of react ion. In two kinds of react ion, the compared stimuli which can be differ

20、ed from the sta ndard stimuli actually can 'be dist in guished to the sta ndard stimuli. Under this kind of situation, we define the 75% times judged as stronger than the standard stimuli as the up threshold of equal district and 25% times judged as stron ger tha n thesta ndard stimuli as the lo

21、wer threshold ofequal district. The half of the equal district is differe nee threshold. However, the differe nee threshold we got i n this way is not conforming to the definition. So we call it 75% differenee threshold.4.2 Space errorWhen measuring the differenee threshold of pitch in the method of

22、 constant stimuli, we should take care of space error. Space error here mea ns the error caused by left ear of right ear. Right ear is con sidered con trolled by left side of brain and the left ear is con trolled by right side of brai n. While differe nt sides of brain are in charge of differe nt ab

23、ility. It means that differe nt side of ear may have differe nt degree of sen sibility of differe nee of pitch. In that case, we n eed coun terbala nee the space error. We can arra nge the same amount of stimuli displayed to both sides of ears or we can display stimuli to both sides of ears at the s

24、ame time.4.3 Time errorBesides the space error, time error also makes a differe nee in this experime nt. Time error represe nts the error caused by the time order of displaying stimuli. Difference threshold measured when the ehangeable stimuli is displayed first may differe nt from the situati on of

25、 the sta ndard stimuli is displayed first. These kinds of error that up or lower threshold are higher of lower than the real value is defined as time error. To counterbalanee the time error, we should make sure that the number of situation where the changeable stimuli is displayed first is equal to

26、the other situati on and ran domly assig nment.5 Con clusi onBy using method of con sta nt differe nee, we can measure the differe nee threshold of pitch. Differe nt people have differe nt differe nee threshold of pitch.Method of con sta nt stimuli is one of the importa nt ways in classicalpsycholog

27、ical physics. When measuring the differenee threshold in this method, we should pay attention to coun terbala nee the time error and the space error. We also n eed to disti net the 75% differe nee threshold and the no rmal differe nee threshold.6 Refere neeBoming Yang心理实验纲要Ying Zhu,2000,实验心理学7 Appe

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