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Effect of Stimulus Uncertainty Essay


The participants of the card sort experiment, were twenty-one psychology students enrolled in psychology 213W. Four of the students were male and seventeen of the remaining students were female. Students participated in this experiment to satisfy a course requirement.


The experiment took place in room 337, the experimental psychology lab room in the science building of Queens College, CUNY.


The participants used a standard deck of playing cards, which had 52 cards in four suits. Participants used cellular devices with 1 second precision, as time keeping devices and a pencil or black or blue ink pen to record data on a piece of paper. The internet based program VassarStats was used to calculate the T-Tests.

Experimental Design

A within-subject counterbalanced experimental design was used for this study (ABBA). In this design, each participant received each condition and served as his or her own control. The independent variable in this experiment was the method of sorting; condition A was a 2-sort alternative and condition B was a 4 sort alternative. The dependent variable in this experiment was the change in the response time, which was measured in seconds. Response time was the time it took the participant to sort all cards into corresponding piles, until the last card is on the table and no longer in the hand of the participant. The Null hypothesis in this study was the differing levels of the independent variable will produce no change in the dependent variable. The alternative hypothesis was the changes in the independent variable would result in changes of the dependent variable.


The twenty-one participants divided into groups of two, because there was an odd number, there was a group of three. When groups were settled into their cubicles, one participant counted the cards, to make sure the deck contained 52 cards. Once the participant finished counting, cards such as joker and informational cards were taken out. The cards were than shuffled, three times, for randomization. Before the experiment could start, one student would take on the role as a participant and the other as the time keeper. The time keeper used their cellular device to time all 4 trials. Before the experiment could begin, the students counted the cards, to make sure that there were 52 cards. After counting the cards, a student used the bridge method to shuffle the cards. Each trial began when the time keeper said “go!” For all four trials, the experimenter timed the participant once he/she began sorting the cards and stopped the time once the participants hand was no longer holding the last card.

Trial 1 (A), included the participant holding the deck of cards face down , and he/she must sort the deck of card into 2 piles, one pile being a black suit pile and the other a red suit pile. In between the trials, the experimenter (also the time keeper) shuffled the cards. Trail 2 (B), again, holding the deck of cards, face down, the participant is asked to sort the cards into 4 piles this time, one for each suit; diamonds, clubs, spades, hearts. Once Trial 3 (B) is finished, the cards are shuffled again and handed to the participant. Trial 4(A), is a repeat of trial 1, the participants had to separate the deck of card into 2 groups, by alternative color.

For each trial, the participant was timed as to how long it took them to complete the sorting, for each trial. The results were recorded on a piece of paper. Once all four trials were completed the experimenter and the participants switched roles. The procedure was repeated for the new participant. After the data was collected, the groups, calculated their means.


Sorting by color (M(mean)=48.33 seconds) was significantly faster then sorting by suit (M(mean)=66.43 seconds). The results were significant at t(-11.78), with p<.0001>. Figure 1 shows the means of the 2 sort groups and the 4 sort groups. The participants were able to sort the cards in condition A significantly faster than condition B. Therefore, we accept the alternative hypothesis and reject the null hypothesis.


Figure SEQ Figure \* ARABIC 1 The Y-Axis represents the averages of the groups. The X-axis shows the two types of sorting methods. Group means were lower for the color sort (2 sort), than for the suit sort (4 sort).

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