NEUROPSYCHOLOGICAL ASSESSMENT LAB

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

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EQUIPMENT CALIBRATION:

Assessment Lab Report 2-1
December/1998

In the series two studies, participants could use either of two IBM compatible computers set at comfortable distance apart on a lab bench. Each of the two computers had VGA screen display with a computer mouse as the primary response mode for most scales. Although this same equipment was used in the series one studies, a calibration study in the series two studies appeared warranted by the introduction in this series of two scales based primarily on auditory presentation of stimuli which combined mouse and keyboard response.

Method

Participants

Two participant samples provided data for this study. A total of 71 subjects provided data used in the calibration studies for the ANAM/TWB cognitive performance tasks. Six additional invalid protocols (evidence of random response) were found in inspection of responses to the CogAttention scale near the end of the test battery. CogAttention was the first scale in which participants were asked to respond to auditory stimuli and use a combination of mouse and keyboard responses. These protocols were eliminated before analysis of the results on the CogAttention and CogMemory scales.

There was no apparent relationship between the invalid protocols and which computer was used. Of the total research sample, 35% used Instrument A and 65% used Instrument B. The corresponding percentages after eliminating the invalid protocols were 31% and 69%. Using the total sample percentages to calculate expected frequencies, this difference was not statistically significant (chi-square (1, N = 65) = .56, p > .05). In addition, t-tests indicated no significant difference on scales other than CogAttention when the sample of 65 was compared with the sample of 71 which included the suspect CogAttention protocols. It would thus appear that the reduced sample is essentially representative of the larger research group with the number of eliminated protocols most likely an artifact of the change in response set.

Instrumentation

The cognitive processing tests selected from the Tester's Workbench (TWB) package for use in the series two studies are designed to run in DOS mode. The computer identified below as Instrument A uses the DOS operating system. The computer identified as Instrument B uses the Windows 95 operating system but was rebooted for MS-DOS mode before administering the tests. Characteristics of the two computers are in the table below.

TABLE 1
COMPUTER CHARACTERISTICS

instrument	model	CPU Type	CPU Clock	Version
A	IBM PS/2 Model 55	80386SX	16 MHz	IBM DOS 4.0
B	PC-Clone	80486DX	66 MHz	Win95 4.0.95

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For Instrument A, sound was provided through headphones connected to an external parallel port device from Digispeech. Volume was controlled with a knob on the external device.

Sound on Instrument B was provided through headphones attached to an internal Sound Blaster card. Volume was controlled on the headphones.

Results

The selection of computer to use (Instrument A or Instrument B) was made by the participant. When only one participant was scheduled during a particular time period, the participants tended to choose the computer further from the entrance. The n for Instrument A is approximately half as large as that for Instrument B.

Table 2 below compares the cognitive efficiency (correct responses/minute) scores obtained by the subjects on the two computers. No significant differences were evident in these data.

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TABLE 2
COGNITIVE EFFICIENCY SCORES
n=71

	Instrument A n=25	Instrument B n=46
	mean (s.d.)	mean (s.d.)	t	p
2-choice	128.3 (21.76)	130.7 (18.29)	.49	.626
react-1	107.4 (10.33)	103.7 (12.63)	1.24	.22
react-2	105.2 (14.01)	98.6 (18.44)	1.55	.126
math	24.9 (6.75)	23.2 (5.25)	1.17	.245
spatial	30.3 (9.21)	31.1 (7.11)	.39	.697
match	33.4 (9.09)	33.5 (9.22)	.08	.940

2-choice: Simple Two-Choice Reaction Time
react-1: Procedural Reaction Time- Standard Stimuli
react-2: Procedural Reaction Time- Degraded Stimuli
math: Mathematical Processing
spatial: Spatial Processing- Simultaneous
match: Matching To Sample

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Table 3 below compares performance of participants using the different computers on the tests with auditory stimuli with combined mouse and keyboard response. As above, differences in mean performance on the two computers were not statistically significant.

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TABLE 3
RAW SCORES ON AUDITORY TESTS
n=65

	Instrument A n=20	Instrument B n=45
	mean (s.d.)	mean (s.d.)	t	p
CogAttention-1	6.9 (2.53)	6.7 (2.58)	.27	.785
CogAttention-2	6.3 (2.13)	7.0 (1.95)	1.21	.229
CogAttention-Tot	13.2 (3.96)	13.7 (3.78)	.45	.652
CogMemory	34.6 (5.51)	35.2 (8.86)	.29	.773

CogAttention-1: Part One of CogAttention (10 items)
CogAttention-2: Part Two of CogAttention (10 items)
CogAttention-Tot: CogAttention Part One + Part Two
CogMemory: Auditory Digit Memory Scale (55 items)

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Summary and Discussion

These data support continued use of both computers as instruments for administration of the cognitive performance scales. The overall power differences in the two computers was not reflected in differences in performance of participants on cognitive scales relying on accurate measurement of response speed. The distinctly different technologies used to produce auditory stimuli appeared equally effective.

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Guide to Reports

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