Influencing performance in a serial addition task.

Refer to the Advances in Cognitive Psychology (Jan.

2013) study of performance in a classic psychological test involving adding a set of numbers, Exercise 9.66

(p. 499). Recall that 300 undergraduate students were given a serial addition task, with the numbers 11,000 +

40 + 1,000 + 30 + 1,000 + 20 + 1,000 + 102 pre sented on a computer screen. However, the students were divided into five groups of 60 students each, and the presentation of the numbers (total display time and color of the number 1,000) was varied in each group: Group 1—2 seconds/

black, Group 2—2 seconds/bright red, Group 3—15 seconds/bright red, Group 4—1 second/black, and Group 5—15 seconds/black. The number of students who gave the correct response of 4,100 was determined as well as the number who gave an incorrect response. The results are summarized (number of responses) in the accompanying table. Does presentation of the numbers to be added influence performance (correct response rate) on the serial addition task? Test, using a = .01.

Presentation Responses of 4,100 Responses of 5,000 Other Incorrect Responses Group 1 (2 sec/black) 17 33 10 Group 2 (2 sec/red) 8 42 10 Group 3 (15 sec/red) 12 36 12 Group 4 (1 sec/black) 13 42 5 Group 5 (15 sec/black) 20 31 9