The California Verbal Learning Test (CVLT)Delis, D. C., Kramer, J. H., Kaplan, E., & Ober, B. A. (1987). CVLT, California Verbal Learning Test: Adult Version: Manual. Psychological Corporation. is one of the most widely used neuropsychological tests in North America. As an instrument, it represents a relatively new approach to clinical psychology and the cognitive science of memory. It measures episodic verbal learning and memory, and demonstrates sensitivity to a range of clinical conditions.Elwood, R. W. (1995). The California Verbal Learning Test: psychometric characteristics and clinical application. Neuropsychology Review, 5(3), 173–201. The test does this by attempting to link memory deficits with impaired performance on specific tasks. It assesses encoding, recall and recognition in a single modality of item presentation (auditory-verbal). The CVLT is considered to be a more sensitive measure of episodic memory than other verbal learning tests. It was designed to not only measure how much a subject learned, but also reveal strategies employed and the types of errors made. The CVLT indexes free and cued recall, serial position effects (including primacy and recency), semantic clustering, intrusions, interference and recognition. Delis et al. (1994) released the California Verbal Learning Test for Children (CVLT-C). The California Verbal Learning Test-II (CVLT-II) is an updated version of the original CVLT, which has been standardized and provides normative data.
Measures CVLT generates a wide variety of measures: Immediate Recall Short Delay Free Recall Short Delay Cued Recall Long Delay Free Recall Long Delay Cued Recall Long Delay Recognition
Administration The original CVLT was normed on a 'reference sample' of 273 nonclinical subjects.Elwood, R. W. (1995). The California Verbal Learning Test: psychometric characteristics and clinical application. Neuropsychology Review, 5(3), 173-201.
The experimenter reads a list of 16 nouns aloud, at one-second intervals, in fixed order, over five learning trials (list A). After each trial, the subject is asked to recall as many words as they can in any order (i.e., free recall).
A big feature, compared to other verbal learning tests, is that the words are drawn from four semantic categories (tools, fruits, clothing, spices and herbs), with no consecutive words from the same category. If a subject 'clusters' words from a category together, it is probable that they are using semantic organisation.
An interference list (list B) is presented that shares two categories from List A (e.g., fruit and tools) and has two unshared categories (e.g., fish and kitchen utensils). However, neither list uses common words for a specific category (e.g., apples used rather than bananas). Free and cued recall of list A are tested immediately (short-delay), and again after 20 minutes (long-delay). In cued recall, the experimenter prompts the subjects with the word category.
The CVLT ends with a recognition task, where the experimenter presents the subject with a 44-word list, and the subject must indicate whether it is a target word or a distractor. Some distractors share semantic categories with the target words while others sound alike. The 44-word list is presented like shopping list as it was argued that this is an activity that people face in their everyday activities. Background participant information about age, sex, and ethnicity are recorded for demographic purposes. The words have an average of 2.37 syllables and 64% of the items on the recognition list are distractors.
Analysis A computer administration and scoring system generates scores for every measure, graphs a learning curve, and provides learning parameters, response errors and interference effects. Raw scores are used for all analyses, ultimately determining how many errors are made in each learning task. The Wilcoxon Signed Rank Test assesses practice effects and Spearman's rho (p) correlation coefficient is conducted to assess test-retest reliability. Primary learning, recall and recognition measures are recorded as well as the more detailed process measures such as errors, contrast scores, and ratio.
It is suggested that a general verbal learning component consistently accounts for about 35-40% of the total variance and consists of total free recall over the five trials of list A, semantic clustering free and cued recall (both short- and long-delays), and recognition hits. A second, "response discrimination" component has also been found in most studies. It accounts for about 8-10% of the variance with loadings from free and cued recall intrusions and recognition false positives. The remaining components, learning strategy (semantic and serial clustering), serial position (primacy and recency) and proactive effect (List B recall) are inconsistent and account for little additional variance.
Applications The results can give the experimenter considerable information about personalities, different conditions and learning difficulties. For example, an anxious participant may perform poorly on the first trial but improve as the task is repeated. Adults with limited learning capacity may perform well on early trials but reach a plateau where repeated trials do not reflect improved performance, or have inconsistent recall across trials. This can happen if they try and fail with different strategies of learning. Studies have demonstrated that inconsistent recall across trials characterises patients with amnesia caused by frontal lobe pathology. Sex: According to some studies, men have worse memory in memorizing a list of words than women. This is consistent with hypotheses linking estrogen levels and verbal memory, as well as the fact that hippocampal atrophy occurs in young men, but not in young women.Kramer, J. H., Yaffe, K., Lengenfelder, J., & Delis, D. C. (2003). Age and gender interactions on verbal memory performance. Journal of the International Neuropsychological Society, 9(01), 97–102. Age: Recall on the CVLT declines with ageCullum, C. M., Filley, C. M., & Kozora, E. (1995). Episodic memory function in advanced aging and early Alzheimer's disease. Journal of the International Neuropsychological Society, 1(01), 100–103. Clinically: Lowered recall has been found in patients with: Traumatic brain injury: CLVT-II after traumatic brain injury to evaluate the sequelae. Deficits in learning and memory are fairly common after moderate to severe TBI, such as those associated to prolonged loss of consciousness and acute intracranial lesions on fMRI. However, it is unusual to have difficulties that persist for extended periods of timeNovack, T. A., Kofoed, B. A., & Crossno, B. (1995). Sequential performance on the California Verbal Learning Test following traumatic brain injury. The Clinical Neuropsychologist, 9(1), 38–43.Curtiss, G., Vanderploeg, R. D., Spencer, J., & Salazar, A. M. (2001). Patterns of verbal learning and memory in traumatic brain injury. Journal of the International Neuropsychological Society, 7(05), 574–585. Evidence suggest that it can detect whether patients are faking head injury in order to gain benefitsSweet, J. J., Wolfe, P., Sattlberger, E., Numan, B., Rosenfeld, J. P., Clingerman, S., & Nies, K. J. (2000). Further investigation of traumatic brain injury versus insufficient effort with the California Verbal Learning Test. Archives of Clinical Neuropsychology, 15(2), 105–113. Frontal lobe lesions: Disruption of different cognitive processes associated with specific frontal regions, underlies the varied patterns of memory impairment, which can be identified using the CVLT.Alexander, M. P., Stuss, D. T., & Fansabedian, N. (2003). California Verbal Learning Test: performance by patients with focal frontal and non-frontal lesions. Brain, 126(6), 1493–1503. Patients with frontal injuries learned fewer words, made more intrusion errors and had impaired recognition performance. The test has shown differentiations within the frontal region. Frontal lobe lesions do not cause classic amnesia, but they can disrupt learning and memory. Alexander et al. (2003) compared 33 patients with focal frontal injury, patients with non-frontal injury and normal controls on the CVLT. Patients with frontopolar lesions performed normally, but subgroups with left posterior dorsolateral frontal lesions or posterior medial frontal region had impaired learning and recall. The former group's impairment is secondary to a mild lexical-semantic deficit. Alzheimer's disease: Patients with Alzheimer's disease are often administered the CVLT in the early stages of the disease, as it is quite a demanding task. In more advanced patients, it has been considered more desirable to use the CERAD-NAB List task.Simon, E., Leach, L., Winocur, G., & Moscovitch, M. (1994). Intact primary memory in mild to moderate Alzheimer disease: Indices from the California Verbal Learning Test. Journal of Clinical and Experimental Neuropsychology, 16(3), 414–422.Beck, I. R., Gagneux-Zurbriggen, A., Berres, M., Taylor, K. I., & Monsch, A. U. (2012). Comparison of verbal episodic memory measures: Consortium to establish a registry for alzheimer's disease-neuropsychological assessment battery (CERAD-NAB) versus California verbal learning test (CVLT). Archives of Clinical Neuropsychology, 27(5), 510–519. Anterior temporal lobectomyDavies, K. G., Bell, B. D., Bush, A. J., & Wyler, A. R. (1998). Prediction of verbal memory loss in individuals after anterior temporal lobectomy. Epilepsia, 39(8), 820–828. Korsakoff's syndromevan Geldorp, B., Bergmann, H. C., Robertson, J., Wester, A. J., & Kessels, R. P. C. (2012). The interaction of working memory performance and episodic memory formation in patients with Korsakoff's amnesia. Brain Research, 1433, 98–103. Huntington's diseaseFine, E. M., Delis, D. C., Wetter, S. R., Jacobson, M. W., Hamilton, J. M., Peavy, G., … Bondi, M. W. (2008). Identifying the "source" of recognition memory deficits in patients with Huntington's disease or Alzheimer's disease: Evidence from the CVLT-II. Journal of Clinical and Experimental Neuropsychology, 30(4), 463–470. Lacunar infarctsWolfe, N., Linn, R., Babikian, V. L., Knoefel, J. E., & Albert, M. L. (1990). Frontal systems impairment following multiple lacunar infarcts. Archives of Neurology, 47(2), 129–132. Right hemisphere strokeWelte, P. O. (1993). Indices of verbal learning and memory deficits after right hemisphere stroke. Archives of Physical Medicine and Rehabilitation, 74(6), 631–636. Left side complex partial seizuresHermann, B. P., Wyler, A. R., Richey, E. T., & Rea, J. M. (1987). Memory function and verbal learning ability in patients with complex partial seizures of temporal lobe origin. Epilepsia, 28(5), 547–554. SchizophreniaPaulsen, J. S., Heaton, R. K., Sadek, J. R., Perry, W., Delis, D. C., Braff, D., … Jeste, D. V. (1995). The nature of learning and memory impairments in schizophrenia. Journal of the International Neuropsychological Society, 1(01), 88–99. Encephalopathy from Lyme diseaseKaplan, R. F., Meadows, M.-E., Vincent, L. C., Logigian, E. L., & Steere, A. C. (1992). Memory impairment and depression in patients with Lyme encephalopathy Comparison with fibromyalgia and nonpsychotically depressed patients. Neurology, 42(7), 1263.