NEUROPSYCHOLOGICAL ASSESSMENT LAB

PAUL JONES, ED.D.
UNIVERSITY OF NEVADA, LAS VEGAS

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NORMATIVE STUDIES:

Assessment Lab Report 1-3
May/1998

This report provides summary data on characteristic response patterns of upper division teacher education students on selected ANAM/TWB instruments. The intent is to provide baseline data for use in future studies, enhancing the capability to use the instruments in placement decisions and to isolate treatment effects. Additional information about the participants used to generate these data and the cognitive test instruments is available in other series one reports.

The format of this report is intended to provide sufficient detail for future investigators to replicate the test conditions. For the ANAM/TWB scales used in this test series, this report includes:

1. a description of the response conditions
2. summary statistics for accuracy and efficiency scores
3. identification of score levels which may be clinically significant

Accuracy is defined as the percentage of correct responses. Efficiency is the number of correct responses per minute. Because accuracy scores on the ANAM/TWB scales are typically high, the efficiency score is likely to be more useful in most applications.

Calculation of the clinical significance levels is based on procedures suggested by Gastaldo, Reeves, Levinson, and Wenger (1997) and by Kay (1995). Scores in the range between the 5th and 15th percentile are identified as suggesting moderate impairment. Scores below the 5th percentile are identified as suggesting significant impairment.

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PROCEDURAL REACTION TIME: Standard Stimuli

In both practice and test trials, the stimuli were presented on the screen for up to 8000 ms with a maximum of 9000 ms allowed for response. Subjects completed a practice trial with 17 stimuli (items). The test trial summarized below used 37 stimuli (items).

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TABLE 1
PROCEDURAL REACTION TIME
Standard Stimuli

	accuracy percent	efficiency score
mean	98.1	100.1
s.d.	3.21	13.54
median	100.0	101.1
maximum	100.0	124.4
minimum	86.7	60.9
75%ile	100.0	109.9
25%ile	96.7	90.4
moderate impairment	91 to 96	79 to 88
significant impairment	0 to 90	0 to 78

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PROCEDURAL REACTION TIME: Degraded Stimuli

The task demand was identical to the standard stimulus condition, but stimuli on the screen were visually distorted and more difficult to identify. In both practice and test trials, the stimuli were presented on the screen for up to 8000 ms with a maximum of 9000 ms allowed for response. Subjects completed a practice trial with 17 stimuli (items). The test trial summarized below used 37 stimuli (items).

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TABLE 2
PROCEDURAL REACTION TIME
Degraded Stimuli

	accuracy percent	efficiency score
mean	97.9	94.1
s.d.	3.49	20.63
median	100.0	95.2
maximum	100.0	131.8
minimum	83.3	42.9
75%ile	100.0	107.4
25%ile	96.7	80.6
moderate impairment	91 to 96	58 to 71
significant impairment	0 to 90	0 to 57

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STERNBERG MEMORY SEARCH: 4-letter and 6-letter memory sets

This test is administered under two conditions. In the first, the memory set is comprised of four letters. In the second, the memory set has six letters. In both conditions, the subjects had practice trials with 10 probes (items). The test trials used 30 probes. In both practice and test, the stimuli were displayed for a maximum of 5000 ms with 5100 ms allowed for response.

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TABLE 3
STERNBERG MEMORY SEARCH
4-letter memory set

	accuracy percent	efficiency score
mean	96.4	80.3
s.d.	5.29	17.29
median	96.7	82.8
maximum	100.0	123.1
minimum	73.3	42.8
75%ile	100.0	90.8
25%ile	96.7	70.7
moderate impairment	83 to 93	48 to 62
significant impairment	0 to 82	0 to 47

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TABLE 4
STERNBERG MEMORY SEARCH
6-letter memory set

	accuracy percent	efficiency score
mean	97.5	80.3
s.d.	4.25	17.80
median	100.0	78.9
maximum	100.0	118.8
minimum	80.0	44.5
75%ile	100.0	92.1
25%ile	96.7	69.2
moderate impairment	90 to 93	47 to 58
significant impairment	0 to 89	0 to 46

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MATHEMATICAL PROCESSING

Math problems using sets of three single-digit numbers, e.g., 5+3-4 = ? are displayed on the screen. The subject determines whether the answer is greater than or less than five, responding by clicking the left or right mouse button. Stimuli (10 in the practice session and 25 in the actual test) are displayed for up to 14900 ms with 15000 ms allowed for response.

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TABLE 5
MATHEMATICAL PROCESSING

	accuracy percent	efficiency score
mean	93.6	24.4
s.d.	5.90	6.39
median	96.0	23.0
maximum	100.0	42.4
minimum	76.0	9.8
75%ile	98.0	28.5
25%ile	92.0	20.1
moderate impairment	84 to 88	15 to 18
significant impairment	0 to 83	0 to 14

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SPATIAL PROCESSING: Simultaneous

Two histograms are displayed simultaneously on the monitor. The histogram on the right is rotated. The subject indicates with click of left or right mouse button whether the two histograms are identical in shape. The practice trial has 10 stimuli (items). The test trial has 25 items. Stimuli are displayed for up to 8000 ms with up to 9000 ms allowed for response.

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TABLE 6
SPATIAL PROCESSING
Simultaneous

	accuracy percent	efficiency score
mean	95.9	28.2
s.d.	7.85	6.78
median	100.0	28.2
maximum	100.0	42.8
minimum	56.0	13.1
75%ile	100.0	33.4
25%ile	96.0	23.2
moderate impairment	76 to 92	17 to 20
significant impairment	0 to 75	0 to 16

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MATCHING TO SAMPLE

A single 4 by 4 matrix with cells of red and yellow is displayed on the screen. The subject initiates the presentation of the test stimulus by clicking a mouse button. The test stimulus consists of two 4 by 4 matrices, side by side on the screen, one of which is identical to the previously presented standard stimulus. The subject clicks the left or right mouse button to identify the identical stimulus. The practice session with this task included five trials (items); the test session has 25 items. The stimulus was displayed for up to 14900 ms with 15000 ms allowed for response.

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TABLE 7
MATCHING TO SAMPLE

	accuracy percent	efficiency score
mean	91.0	30.0
s.d.	9.89	10.13
median	96.0	28.3
maximum	100.0	59.6
minimum	56.0	11.4
75%ile	96.0	33.2
25%ile	88.0	24.3
moderate impairment	65 to 84	15 to 21
significant impairment	0 to 64	0 to 14

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COMPARISON WITH OTHER SAMPLES

Table 8 below provides data for comparison with other sample groups. The information in Table 8 must be interpreted with a great deal of caution. Neither conditions of administration nor actual stimuli were identical with those used in this study. These data, thus, provide only a rough estimate of comparable performance.

The group identified as USMC was comprised of 197 (83 females and 114 males) United States Marine Corps recruits (Gastaldo, Reeves, Levinson, & Wenger, 1997). The age range was 17 to 26 with an average age of 18. The average number of years of education was 12.

The group identified as UOk was comprised of 64 male subjects from the University of Oklahoma and 15 male subjects from Wright State University (Schlegel, Gilliland, & Crabtree, 1992). The age range was 18 to 36 with an average age of 21. Approximately one-half were lower division students. Cognitive efficiency scores were not available for this sample

The group identified as TBI was comprised of 22 patients (11 male and 11 female) participating in a traumatic head injury rehabilitation program (Levinson & Reeves, 1997). All had sustained traumatic brain injuries, most from motor vehicle accidents. The ages ranged from 18 to 64 with an average of 38. The average number of years of education was 13. Data from three groups classified according to severity of injury (marginal-mild: n=8), mild-moderate: n=7), and moderate: n=7) were combined in Table 8. Mean response time for correct responses was not reported for these subjects.

Considering the caution noted above about lack of identical administration conditions, the data in Table 8 are essentially as would be anticipated, including high accuracy scores of the nonclinical groups. In comparison of this sample with the USMC sample, the marked difference in efficiency on the Sternberg Memory Search with the six-letter set is probably based on a much longer test used with the USMC group. Otherwise, the performance appeared essentially consistent.

Efficiency scores were not available for the UOk group, but a significantly faster response time was evident on the comparable scales. This could be the result of a different response mode (keyboard vs. mouse). Even more relevant may be that the UOk data were gathered after the subjects had multiple trials with the cognitive scales.

As anticipated, the TBI group had significantly lower accuracy and efficiency scores. In each instance the reported score met the criteria for classification as impaired identified in the tables above.

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TABLE 8
COMPARISON WITH OTHER SAMPLES

	UNLV				USMC				UOk			TBI
	Acc	Eff	RT		Acc	Eff	RT		Acc	RT		Acc	Eff
react-1	98	100	599		n/a	n/a	n/a		98	562		92	86
react-2	98	94	654		n/a	n/a	n/a		96	638		n/a	n/a
mem-4	96	80	751		n/a	n/a	n/a		97	552		75	57
mem-6	98	80	763		91	51	1114		n/a	n/a		n/a	n/a
math	94	24	2470		93	21	2920		98	1522		80	12
spatial	96	28	2165		90	24	2484		n/a	n/a		87	15
match	91	30	1893		91	37	1563		n/a	n/a		n/a	n/a

Acc: accuracy (percentage of correct responses)
Eff: efficiency (correct responses per minute)
RT: mean response time for correct responses (ms)

react-1: Procedural Reaction Time- Standard Version
react-2: Procedural Reaction Time- Degraded Stimuli
mem-4: Sternberg Memory Search- Four-Letter Set
mem-6: Sternberg Memory Search- Six-Letter Set
math: Mathematical Processing
spatial: Spatial Processing- Simultaneous
match: Matching To Sample

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References

Gastaldo, E., Reeves, D., Levinson, D., & Wenger, C.B. (1997). ANAM normative data: USMC-1995 hyponatremia outbreak studies. San Diego, CA: National Cognitive Recovery Foundation.

Levinson, D.M., & Reeves, D.L. (1997). Monitoring recovery from traumatic brain injury using Automated Neuropsychological Assessment Metrics (ANAM V1.0). Archives of Clinical Neuropsychology, 12, 155-166.

Kay, G. (1995). Cogscreen: Aeromedical edition: professional manual. Odessa, FL: Psychological Assessment Resources, Inc.

Schlegel, R.E., Gilliland, K., & Crabtree, M.S. (1992). Development of the UTC-PAB Normative Database: Technical Report. Springfield, VA: National Technical Information Service.

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Guide to Reports

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