Symbol Digit Modalities Test incidental learning: Concurrent validity and clinical utility

This project examined the Incidental Learning (IL) procedure from the Symbol-Digit Modalities Test (SDMT) as both a screening tool and as a measure of memory. Participants included undergraduate college students and stroke- and dementia-free older adult volunteers with and without hypertension or chronic kidney disease. In each sample, IL scores were correlated with performances from a variety of cognitive tasks. Results indicated that IL scores were more strongly associated with tests of memory than other cognitive abilities. As a screening instrument for older adults, scores of four or more recalled symbol-digit pairings strongly indicated a lack of difficulties on other tests of memory, whereas scores of three or fewer suggested a need for further assessment, though not necessarily impairment. A novel recognition (IL-r) procedure was introduced to older participants without kidney disease, and results indicated that IL-r uniquely predicted both delayed verbal and visual memory beyond standard IL. Our findings suggest that IL can be regarded as an efficient supplemental or screening test of memory that offers a complementary methodology to a comprehensive assessment of memory.