Abstract
Spatial span tests (SSTs) such as the Corsi Block Test (CBT) and the SST of the Wechsler Memory Scale are widely used to assess deficits in spatial working memory. We conducted three experiments to evaluate the test–retest reliability and clinical sensitivity of a new computerized spatial span test (C-SST) that incorporates psychophysical methods to improve the precision of spatial span measurement. In Experiment 1, we analyzed C-SST test–retest reliability in 49 participants who underwent three test sessions at weekly intervals. Intraclass correlation coefficients (ICC) were higher for a psychophysically derived mean span (MnS) metric (0.83) than for the maximal span and total correct metrics used in traditional spatial-span tests. Response times (ReTs) also showed high ICCs (0.93) that correlated negatively with MnS scores and correlated positively with response-time latencies from other tests of processing speed. Learning effects were insignificant. Experiment 2 examined the performance of Experiment 1 participants when instructed to feign symptoms of traumatic brain injury (TBI): 57% showed abnormal MnS z-scores. A MnS z-score cutoff of 3.0 correctly classified 36% of simulated malingerers and 91% of the subgroup of 11 control participants with abnormal spans. Malingerers also made more substitution errors than control participants with abnormal spans (sensitivity = 43%, specificity = 91%). In addition, malingerers showed no evidence of ReT slowing, in contrast to significant abnormalities seen on other malingered tests of processing speed. As a result, differences between ReT z-scores and z-scores on other processing speed tests showed very high sensitivity and specificity in distinguishing malingering and control participants with either normal or abnormal spans. Experiment 3 examined C-SST performance in a group of patients with predominantly mild TBI: neither MnS nor ReT z-scores showed significant group-level abnormalities. The C-SST improves the reliability and sensitivity of spatial span testing, can accurately detect malingering, and shows that visuospatial working memory is largely preserved in patients with predominantly mild TBI.
Highlights
Spatial span tests (SSTs) have been widely used to evaluate visuospatial memory in patients with such diverse disorders as dementia (Wiechmann et al, 2011), schizophrenia (Chey et al, 2002), Parkinson’s disease (Yaguez et al, 2006), stroke (Kessels et al, 2000), post-traumatic stress disorder (PTSD) (Flaks et al, 2014), and ADHD (Yang et al, 2011)
We describe a computerized spatial span test (C-SST) that provides multiple measures of visuospatial memory span, including the maximal span metric of the Corsi Block Test, the total correct metric of the Wechsler Spatial Span Test, and the psychophysically based mean span (MnS) metric
Experiment 1 revealed that response times (ReTs) were highly reliable across tests, and that learning effects on both MnS and ReT scores were insignificant
Summary
Spatial span tests (SSTs) have been widely used to evaluate visuospatial memory in patients with such diverse disorders as dementia (Wiechmann et al, 2011), schizophrenia (Chey et al, 2002), Parkinson’s disease (Yaguez et al, 2006), stroke (Kessels et al, 2000), PTSD (Flaks et al, 2014), and ADHD (Yang et al, 2011). The most familiar SST is the Corsi Block Test (CBT) (Berch et al, 1998), in which the participant is presented with a set of nine blocks fixed on a board. Two trials are tested at each length, with trial length increasing if the participant reproduces either or both of the two sequences correctly. Testing ceases when the participant misses both trials of the same length. Maximal span is quantified as the length of the longest sequence correctly reproduced. Instead of quantifying maximal span, the sum of the number of correct trials is recorded (Wechsler, 1997; Wilde et al, 2004; Lo et al, 2012)
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