The OSPAN task (Turner & Engle, 1989) is a frequently used measure of WMC that has two components: the processing of mathematics problems and the simultaneous maintenance in memory of a small number of words in their serial or-der. Higher accuracy on the memory component of the OSPAN task is considered to reflect a higher WMC and Gf. Performance on the mathematics component of the task is not often reported, but in the current experiment both components of the task will be addressed, given the uncertainty regarding the most appropriate measures of the letter-crossing task. Given the outcomes of Experiment 1, a tentative expectation is that those participants who maintain high levels of target identification on the let-ter-crossing task will have scored higher in accuracy on both maths and word compo-nents of the OSPAN pre-task. Again, given the previous outcomes, the other letter-crossing task measures may not be related to the other letter-letter-crossing measures.
5.3.1. Method.
5.3.1.1. Participants. The participant sample was 145 adult volunteers, 55.2% reported being female. The average age was 45.21 years (SD = 19.24) with a range of 19 – 64 years. Recruitment was conducted in the same manner as Experi-ment 1.
5.3.1.2. Materials and procedure. The procedure followed the same sequential-task paradigm as the first experiment. After gaining participant consent, participants filled out a basic demographic questionnaire, before receiving instruc-tions for the first operation span task (OSPAN).
The OSPAN task consisted of eight trials made up of four simple arithmetic problems for immediate responding and four words for later recall. Sixteen trials were created by randomly pairing 64 maths operations and 64 word items. The oper-ations consisted of two parts, the first part contained a multiplication or a division operation, followed by an addition or subtraction operation by a third number, and the total sum, for example, 4/2 + 1 = 3. Half the mathematical operation trials were
correct, the other half were incorrect. Incorrect answers were never more than plus or minus two from the correct answer. The words were one-syllable words between three to six letters in length. Half of the trials were used on the pre-depletion test; the latter was used on the post-depletion task.
Each trial began with an equation of which the participant had four seconds to decide whether this operation was correct by responding true or false before a word item was presented for one second followed by an equation item, and so on. The task was presented via PowerPoint at a programed pace in Calibri font, size 48. Each trial contained eight items presented one per slide; four simple arithmetic equations (cor-rect or incor(cor-rect) and four word items.
After the instructions were outlined, participants were given two practice tri-als to ensure they understood the task instructions. For the word items, participants were encouraged to read each item aloud during presentation for easier recall when prompted by a row of question marks (??????). Participants wrote the four words on a participant response sheet at the end of each trial. The experimenter recorded par-ticipant responses to the mathematical equations. The study instructions stressed that the task was difficult and for participants to make the correct response to the mathe-matical equations and do their best on recalling the words in serial order. Participants were encouraged to leave a space blank if an item could not be remembered. The de-pendent measures were the number of words correctly recalled in their serial position and the number of correctly identified operations. Following the administration of the first OSPAN task session, participants completed the letter-crossing task, and then completed the remaining trials of the OSPAN task.
5.3.2. Results and discussion.
Experiment 2 reported strong power, N = 145, α = .05, β = .14, Power = .86, with a minimum critical r value of 0.16. Pearson’s r was calculated between OSPAN components (maths and word) and average accuracy, completion time, total slope, and average distractor (ie or ei) recalls on the letter-crossing task (N = 145) as out-lined in Table 5.3.
Table 5.3
Descriptive and Correlational Statistics Between OSPAN (Maths and Word) and Letter-Crossing Task Performance (Accuracy, Total Time, Slope, and Distractors Identified)
OSPAN Pre-Task Letter-Crossing Task
Maths Word Average
Accu-racy
Total Time Total Slope Average Distractor M (SD) 26.81 (5.8) 19.92 (7.29) .75 (.16) 17.06 (8.23) -.04 (.05) 1 (2.27)
OSPAN Pre-Task r r r r r r
Maths 1 .28** .46** -.25** -.03 -.15
Word .28** 1 .37** -.35** -.02 -.15
Note. Correlation is significant at the 0.01 level (**) and 0.05 level (*).
The maths and word components of the OSPAN task were highly correlated with each other, again suggesting that there is some common cognitive process un-derpinning both tasks. Both components of the OSPAN task were significantly re-lated to letter-crossing accuracy, and time measures. This suggests those who main-tained high levels of accuracy and who completed the letter-crossing task quickly were more accurate on both the processing and memory components of the OSPAN task. In this experiment, neither the slope nor the distractor measures were related to either component of the OSPAN task. Again, hierarchical regressions were con-ducted to look at the contribution of the individual measures of the letter-crossing task. Refer to Table 5.4. In this instance, accuracy and completion times both made independent contributions to the two OSPAN task components.
Table 5.4
Unique Contribution of the Different Letter-Crossing Measures to the Components of the OSPAN Task
OSPAN Pre-Task Com-ponent
Letter-Cross-ing Measure
R2 Change F Change p value
Maths Average
Ac-curacy
.22 36.34 < .001
Total Time .06 11.33 .001
Word Average
Ac-curacy
.14 22.24 < .001
Total Time .11 21.07 <.001
The outcomes of this study replicate a number of findings from Experiment 1.
Firstly, the accuracy scoring measure is significantly correlated with all components on the outcome task. The results from Experiments 1 and 2 suggest that letter-cross-ing accuracy, whatever this ability is assessletter-cross-ing, is accountletter-cross-ing for performance on all subtasks of the Stroop colour word task and all components of the OSPAN task. In-terestingly, letter-crossing completion time is also a contributing factor to both OSPAN task components and to the colour-word naming subtask of the Stroop col-our word task (Golden & Freshwater, 1978). These three measures would be consid-ered to be measures of executive function, whereas word-reading and colour-naming
Stroop subtasks would not. At this point, the data suggests that a combination of ac-curacy and completion time is related to executive functioning.