Use of VIP^® Test for Persons With Mental Retardation

About the VIP Test | Review of the VIP Test

The following text comes from the VIP (Validity Indicator Profile) Manual, product number 51767.
Frederick, R. I. (1997). VIP (Validity Indicator Profile) Manual. Minneapolis: NCS Pearson, Inc.
Excerpted from the VIP (Validity Indicator Profile) Manual. Copyright © 1997, 2003 NCS Pearson, Inc. All rights reserved.

The 40 persons with mental retardation were included in the cross-validation sample to provide normative data and information about VIP applicability in this clinically important population. Tables 1 and 2 below provide normative data on VIP scores and Performance Curve measures for this group. Tables 3 and 4 show the VIP response style classifications for this group on the Nonverbal and the Verbal subtest, respectively, as well as the mean Shipley IQ for each classification group.

As shown in Tables 1 and 2, on both VIP subtests the mean Total Score for those individuals with a bona fide history of mental retardation was higher than that for the computer-generated random protocols but lower than that for all other participant groups, including the "noncompliant" coached normals and patients at risk for malingering. Although there is no reason to believe that these individuals did not cooperate with the testing, only 20% received a Compliant classification on the Nonverbal subtest (Table 3), and only 25% on the Verbal subtest (Table 4). An Irrelevant classification was received by about a third of this sample on the Nonverbal subtest, and by half the group on theVerball subtest.¹

The Shipley IQs of these individuals ranged between 54 and 75. Despite this limited range, there was nevertheless a pronounced relationship between IQ and VIP response style classification. On both subtests, subjects classified as Compliant had a higher mean IQ than those classified as Inconsistent, who in turn had a higher mean IQ than those classified as Irrelevant. The rightmost columns of Tables 3 and 4 show the effect on VIP response style classification of dividing the overall sample at the median IQ of 64.5. On both subtests, the performance of those with IQs above the median was much more likely to be classified as Compliant, whereas the performance of those with IQs below the median was much more likely to be classified as Irrelevant.

The relationship between IQ and VIP response style classification in this sample of low-IQ individuals suggests that those with extremely low ability may stop trying after they encounter more difficult items mixed among easy ones. The organization of items on the VIP test is randomized with respect to difficulty, and some individuals may assume after trying the first few that they will not know the answers to any items. Accordingly, they may simply fill in the answer blanks randomly after a few items.

If this hypothesis is true, special test administration techniques may help individuals with low ability who want to perform well to persist in attempting items, thereby increasing their Total Score and their chances of receiving a Compliant response style classification. It is permissible to administer the Nonverbal items by individually pointing to each item and asking for a response, encouraging the individual to attempt each item. For the Verbal items, it is permissible to say, "Answer the ones you know; then try the other ones after that. It's okay to guess." Instructions such as these can help individuals who appear to have low ability maintain participation in the task.

In summary, the data presented here recommend against the use of the VIP test to evaluate the validity of cognitive testing for persons who are known from historical information to have bona fide mental retardation; too many cooperative individuals may be mistakenly classified as not cooperating fully with the testing. On the other hand, it is common in many examination settings to encounter individuals who perform extremely poorly on cognitive tests but who are not known from other evidence to have mental retardation. In these instances, malingering must be considered as a possible explanation for the low ability score, and use of the VIP test is appropriate. The interpretation of the VIP results in this situation is addressed in Chapter 7 of the VIP (Validity Indicator Profile) Manual.

Table 1: Nonverbal Subtest Statistics by Participant Group

	Compliant Groups						Noncompliant Groups									Persons With Mental Retardation
	Honest Normals			Brain Injury Patients			Patients at Risk for Malingering			Coached Normals			Random Protocols
	n	M	SD	n	M	SD	n	M	SD	n	M	SD	n	M	SD	n	M	SD
Total Score	100	87.6	9.8	61	78.6	11.8	49	74.2	14.2	52	63.7	16.2	50	50.8	5.1	40	56.7	8.3
Adjusted Score	100	75.5	17.9	61	57.3	23.5	49	49.1	27.0	52	34.6	24.4	50	8.0	6.4	40	16.4	13.7
Performance Curve Measures^a
Sector 1 Distance	100	70.3	20.1	59	52.6	21.5	45	47.8	27.0	33	36.2	26.6	1	^_b	^_b	26	18.0	16.5
Sector 2 Distance	88	13.8	10.1	59	18.9	13.7	42	17.4	11.0	32	23.6	15.0	1	^_b	^_b	26	18.7	13.2
Sector 3 Distance	53	18.9	20.6	48	26.2	20.9	36	35.9	21.5	31	36.0	25.1	1	^_b	^_b	26	56.3	17.7
Sector 1 Residual	100	.012	.010	59	.018	.015	45	.029	.029	33	.044	.030	1	^_b	^_b	26	.060	.036
Slope	100	-.004	.002	61	-.005	.002	49	-.005	.003	52	-.004	.003	50	.000	.002	40	-.004	.003
Point of Entry	100	.99	.02	61	.96	.09	49	.93	.13	52	.78	.22	50	.51	.13	40	.77	.21
Peak Performance Interval	94	36.3	23.0	49	28.8	20.6	34	26.9	15.2	14	14.0	9.4	0	^_	^_	9	9.4	11.2
Suppression Sector Distance	1	^_b	^_b	0	^_	^_	4	22.8	1.7	4	44.3	15.0	1	^_b	^_b	0	-	-
Suppression Sector Starting Point	1	^_b	^_b	0	^_	^_	4	65.8	6.7	4	23.3	18.2	1	^_b	^_b	0	-	-

^aSee Chapter 4 of the VIP (Validity Indicator Profile) Manual for an explanation of the rules that underlie the varying sample sizes for different Performance Curve measures.
^bStatistics are not reported for Performance Curve measures that apply to fewer than two cases.

Table 2: Verbal Subtest Statistics by Participant Group

	Compliant Groups						Noncompliant Groups									Persons With Mental Retardation
	Honest Normals			Brain Injury Patients			Patients at Risk for Malingering			Coached Normals			Random Protocols
	n	M	SD	n	M	SD	n	M	SD	n	M	SD	n	M	SD	n	M	SD
Total Score	100	64.5	4.2	60	58.1	7.5	48	59.5	8.0	52	49.4	12.3	50	39.3	4.3	40	45.6	7.2
Adjusted Score	100	51.0	8.5	60	39.2	12.0	48	41.5	14.7	52	27.3	16.8	50	6.4	5.6	40	15.1	12.4
Performance Curve Measures^a
Sector 1 Distance	100	51.5	9.1	57	40.5	14.6	46	45.1	13.7	40	26.5	19.2	1	^_b	^_b	19	20.2	12.3
Sector 2 Distance	100	10.0	6.6	57	13.8	10.0	46	10.5	6.9	40	19.2	11.8	1	^_b	^_b	19	14.8	9.3
Sector 3 Distance	44	8.5	4.7	45	12.0	9.4	29	14.1	9.9	33	21.8	15.8	1	^_b	^_b	19	28.1	15.0
Sector 1 Residual	100	.008	.007	57	.015	.012	46	.014	.009	40	.034	.029	1	^_b	^_b	19	.041	.037
Slope	100	-.008	.003	60	-.009	.003	48	-.009	.003	52	-.006	.006	50	.000	.003	40	-.004	.005
Point of Entry	100	1.00	.02	60	.97	.13	48	.97	.13	52	.85	.24	50	.46	.16	40	.74	.23
Peak Performance Interval	97	34.0	11.5	54	23.6	12.8	44	25.0	14.6	27	15.4	14.3	0	^_	^_	12	12.3	8.0
Tail Score	100	1.7	1.2	60	1.7	1.6	48	1.5	1.1	52	2.5	1.5	50	4.0	1.3	40	3.4	1.6
Suppression Sector Distance	0	^_	^_	1	^_b	^_b	0	^_	^_	5	41.4	14.7	1	^_b	^_b	0	-	-
Suppression Sector Starting Point	0	^_	^_	1	^_b	^_b	0	^_	^_	5	9.6	17.1	1	^_b	^_b	0	-	-

Table 3: Performance of Persons With Mental Retardation on the Nonverbal Subtest

Response Style Classification	Total Group			IQ < 64 or = 64		IQ = 65 or > 65
	n	%	Mean IQ	n	%	n	%
Compliant	8	20	68.9	1	5	7	35
Inconsistent	18	45	63.6	10	50	8	40
Irrelevant	14	35	62.6	9	45	5	25
Suppressed	0	0	-	0	0	0	0
Total	40	100	64.3	20	100	20	100

Table 4: Performance of Persons With Mental Retardation on the Verbal Subtest

Response Style Classification	Total Group			IQ < 64 or = 64		IQ = 65 or > 65
	n	%	Mean IQ	n	%	n	%
Compliant	10	25	70.8	0	0	10	50
Inconsistent	9	23	65.4	4	20	5	25
Irrelevant	20	50	60.7	15	75	5	25
Suppressed	1	3	60.0	1	5	0	0
Total	40	100	64.3	20	100	20	100

Footnotes

¹ The one person with mental retardation who received a Suppressed response style classification on the Verbal subtest almost certainly employed random responding rather than deliberate suppression. As noted in Chapter 4 of the VIP (Validity Indicator Profile) Manual, purely random protocols will be misclassified as Suppressed about 6 % of the time.

To Reach a Client Relations Representative

Call: 1-800-627-7271
7 AM-6 PM CST
Fax: 1-800-632-9011 or 952-681-3299
E-Mail: pearsonassessments@pearson.com

Adult Personality - Adolescent Personality - Biopsychosocial - Careers - Achievement/Cognitive
Home - News - Products A to Z - Ordering - Resources - Scoring - Support - Contact

		Customer Relations: 800-627-7271 (7 AM-6 PM CST) International Distributors pearsonassessments@pearson.com
	Copyright © 2008 Pearson Education, Inc. or its affiliates. All rights reserved. Trademarks \| Disclaimer \| Privacy Policy \| HIPAA Regulations and FAQ's