A Computerized Test of Design Fluency

Abstract

Tests of design fluency (DF) assess a participant's ability to generate geometric patterns and are thought to measure executive functions involving the non-dominant frontal lobe. Here, we describe the properties of a rapidly administered computerized design-fluency (C-DF) test that measures response times, and is automatically scored. In Experiment 1, we found that the number of unique patterns produced over 90 s by 180 control participants (ages 18 to 82 years) correlated with age, education, and daily computer-use. Each line in the continuous 4-line patterns required approximately 1.0 s to draw. The rate of pattern production and the incidence of repeated patterns both increased over the 90 s test. Unique pattern z-scores (corrected for age and computer-use) correlated with the results of other neuropsychological tests performed on the same day. Experiment 2 analyzed C-DF test-retest reliability in 55 participants in three test sessions at weekly intervals and found high z-score intraclass correlation coefficients (ICC = 0.79). Z-scores in the first session did not differ significantly from those of Experiment 1, but performance improved significantly over repeated tests. Experiment 3 investigated the performance of Experiment 2 participants when instructed to simulate malingering. Z-scores were significantly reduced and pattern repetitions increased, but there was considerable overlap with the performance of the control population. Experiment 4 examined performance in veteran patients tested more than one year after traumatic brain injury (TBI). Patients with mild TBI performed within the normal range, but patients with severe TBI showed reduced z-scores. The C-DF test reliably measures visuospatial pattern generation ability and reveals performance deficits in patients with severe TBI.

Conflict of interest statement

Competing Interests: DLW is affiliated with NeuroBehavioral Systems, Inc., the developers of Presentation software that was used to program these experiments. This does not alter the authors' adherence to the data sharing policies of PLOS ONE.

Figures

Fig 1. The design fluency test.

Participants connected circles on the display with four lines drawn with the mouse. As each line was drawn, the path was shown in white. When the cursor crossed a circle, it was included in the figure and connected with the previously selected circle by a straight green line. When a design was finished, participants moved the cursor (small gray square) to click the “NEXT” box to advance to the next trial.

Fig 2. The number of unique patterns produced in 90s as a function of participant age.

The age-regression slope from Experiment 1 (blue diamonds) is shown, along with the results from the first test session of Experiment 2 (2a, open red squares), Experiment 3 (simulated malingering, green triangles), and Experiment 4 shown separately for patients with mild TBI (mTBI, filled red circles), and severe TBI (sTBI, striped red circles).

Fig 3. Unique pattern z-scores as a function of age.

Z-scores showing the number of unique patterns produced from participants as a function of age after correction for the effects of age and computer use. The red line shows the p

Fig 4. Mean item-selection latencies

The latency of selection for circle 1 was measured from the beginning of the display, and latencies of each subsequent circle and the “NEXT” response were measured relative to the selection of the previous circle. Error bars show 95% confidence intervals. Data from successive correct 4-line patterns in Experiment 1.

Fig 5. Pattern production rate.

The number of unique patterns (top) and repeated patterns (bottom) produced over successive 15 s intervals by the participants in Experiment 1. Error bars show standard errors of the mean.

Fig 6. Test-retest reliability.

Z-scores from each subject in Experiment 2a are shown plotted against z-scores from Experiment 2b (blue diamonds) and Experiment 2c (red squares). Pearson correlations were 0.53 between 2a and 2b, 0.48 between 2a and 2c, and 0.66 between 2b and 2c. The overall intraclass correlation coefficient was 0.79.