Application of Weber’s Law on Visual Perception

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Subject

The experiment was done in a laboratory in Educ Bldg room 306 with the 3rd year BS PSY students specifically, the class of BS5B as the subjects. The experiment was done individually. The participant in this specific experiment is an 18-year old lady. They were given time to draw the lines as stated above. Then, they were given instructions to find the ‘subjective’ midpoint of each line. Finally, they were asked to find the ‘objective’ midpoint using a ruler, measure the error and compute for the average error for each set of lines.

Results

The average error regardless of signs is indicated as Mean 1. When signs are taken into account, the average errors are computed by dividing the first mean by 32, the second by 64, and the third by 96. In doing this, you are in effect, determining the ratio of error to the size of the line.

Table I

Amount and Direction of Error in Judging the Midpoint of Lines with Varying Length

Trial

2-inch Line

4-inch Line

6-inch Line

1

0

-0.06

+0.13

2

-0.06

0

-0.06

3

-0.06

0

+0.06

4

0

+0.13

0

5

0

0

-0.06

6

0

-0.06

0

7

0

0

+0.13

8

0

0

0

9

-0.06

-0.06

+0.13

10

0

0

+0.25

Mean 1

0.018

0.031

0.082

Mean 2

-5.63x10-4

-7.8x10-5

6.04x10-4

Discussion

The experiment was done in a laboratory the building of Educ., room 306. The participants were 3rd year psychology majors from the class of BS5B. The experiment was done individually. Each student was asked to prepare a short bond, a pen and a ruler. They were instructed to draw 10 lines with the length of 2-, 4-, and 6-inches on the bond paper. The only rule was that there should be no consecutive line drawn with the same length. After that, they were told to cover the bond paper that we were holding so that we could only see one line after line and we should get the estimated midpoint without the use of any measuring materials. Then they computed for the Mean 1 which is the average error of each length disregarding the signs, and the Mean 2 which is the average error considering the signs and the mean should be divided by 32, 64 and 96 respectively.

The results could be more accurate if the dots were put clearly and somehow equal for each line. Because some tend to draw a larger dot to make the objective midpoint touch or meet with their estimated or subjective midpoint. Like in the study of Ono, Gonzalez, & Lillakas (2014) they had stated that the point or dot has a location though there were no problem with the just noticeable difference of the objective and subjective dots, there could be a variation of results with the effect of the small details that can be seen in one experiment.

According to Choo & Franconeri (2013), people who can estimate or rapidly have perfect counts of an object once to four times consecutively is called the subitizing. This could also enhance estimation which would be very useful in experiments such as what the subjects had done, and this could lead to a lesser average error in both mean 1 and 2.

Aside from the errors stated above, two lines being almost abreast could cause inaccuracy because it can affect the decision of the subject for they can base their decision on the next line by what they have done in the previous ones. These would invalidate the study because the study aims to measure the judgment per size of the line and the other lines were covered during the process of choosing a midpoint. Likewise, the right procedure will not be followed which alone can invalidate the whole experiment.

Better and deeper understanding of the experiment should be a must for the subjects to get a grasp of what they were really doing and what the study is for because definitions alone is not as efficient compared to the one that was also discussed since the topic of the experiment was not really familiar to all.

Conclusions

Based from the experiment that has been conducted, the 2-inch line could be the easiest line in estimating its midpoint because looking at the table, the subject gained both the lowest means in the 2-inch line. As for the 6-inch line, it is where the subject obtained more mistakes which could led to a conclusion that this line is more difficult to measure because of its length. Lastly, looking at the table closely, the subject had a negative mean 2 for the 2- and 4-inch lines which means that the errors