9.3.1.1. WAIS-R.
A num ber of reports have suggested th a t abbreviated versions of the WAIS/WAIS-R may offer an economical m easure, in term s of time, w ithout compromising validity. Given the num ber of subjects it was thought appropriate to use an abbreviated version in th is study. There are several different short forms available (eg Britton and Savage, 1966; Crawford et al, 1992; CR Reynolds et al, 1983;
Süverstein, 1982; W arrington et al, 1986), and American research h a s suggested th at some 80% of clinicians use an abbreviated version (Holmes et al, 1965). Crawford et al (1992) com pared the psychometric properties of these shortened forms an d found th a t a version described by W arrington et al (1986) was the m ost valid of those reported upon. In the study presented here, th is abbreviated version was used: a verbal IQ is pro-rated from four su b -tests
(Arithmetic, Digit Span, Vocabulary, and Similarities); Performance IQ is pro-rated from three su b -tests (Block Design, Picture
Completion an d Picture Arrangement).
W arrington et al (1986), in a large consecutive series of 656
patients with unilateral cerebral lesions, assessed the validity of the WAIS (the abbreviated version outlined above) a s a localising and lateralising instrum ent. Statistical analysis revealed th a t the WAIS’s ability a t detecting precise localised deficits was minimal. Despite the lack of m any consistent findings, the au th o rs concluded:
"The WAIS provides standardised baseline information a s to the individuals level o f functioning an d identifies impairments requiring more detailed analysis. The WAIS is undoubtedly a useful screening test that provides a fir s t approximation to the functional strengths and
w eaknesses in an individuals cognitive skills. ”
Warrington e t al., 1986 p 238
Initially, patients with frontal lobe dam age were found not to be deficient on IQ m easures com pared to others [eg Hebb, 1945; Mettler, 1949]. Indeed, a common observation was a relative
preservation of WAIS IQ, with dam age caused by either tu m o u r (eg Sm ith, 1966) or surgery for epilepsy (Milner, 1975). Such results, however, do not indicate th a t frontal lobe lesions have no affect on WAIS scores a t all: Milner’s patients showed an average loss of 7.2 IQ points after surgery. There is evidence to suggest th a t orbitofrontal dam age produces little im pairm ent, an d th u s dam age to the
dorsolateral regions is responsible for the deficits th a t do occur (Girgis, 1971). It h as also been suggested th a t left frontal dam age can produce larger IQ falls th a n right sided dam age (Smith, 1966).
9.3.1.2. National Adult Reading Test (NART).
The assessm en t of optimal, or pre-m orbid intellectual ability can be considered an essential p art of any neuropsychological research with neurologically dam aged subjects. The underlying cortical dam age may extend to further regions and have a global im pact on the intellectual function of the individual; th u s the focal dam age may not be the only cause of the cognitive deficit noted.
The National Adult Reading Test (NART; Nelson, 1982) is a m easure designed to a ssess pre-m orbid ability. The test consists of 50
irregular words printed in order of increasing difficulty, to be read by the subject. Two studies reported by Nelson (1982) suggested th a t the NART h a s reasonable levels of both reliability and validity. S ubsequent studies have also confirmed this (BeardsaU and Brayne,
1990; Crawford et al, 1991, 1992; Sharpe and O'CarroU, 1991).
9.3.2. Language and memory Tests.
9.3.2.1. Graded Naming Test (ONT).
The GNT (McKenna and W arrington, 1983) consists of thirty black and white Une draw ings which are presented in ascending order of difficulty. The subject's ta sk is to nam e each of the drawings in tu rn . R esults have suggested a high degree of reUabfiity an d vaUdity.
Furtherm ore, evidence h as suggested th a t th e GNT is able to discrim inate norm al controls from left hem isphere dam aged subjects (McKenna and W arrington, 1983).
Q.3.2.2. De Renzi Token Test.
The test used was an abbreviated version of the original token test (De Renzi an d Vignola, 1962). The patient is asked to perform operations with a set of twelve shapes (four circles, four squares, four triangles), coloured in red, blue, green or yeUow. The test necessitates memory for verbal sequences an d com prehension of verbal com m ands of increasing complexity. Im pairm ent on this m easure indicates disruptive Unguistic processes commonly associated with left (mainly posterior) tem poral lobe dysfunction.
9.3 2.3. Recognition Memory Tests (RMTs).
The Recognition Memory Tests (RMTs) were developed by Warrington (1974) to assess adult global am nesic patients.
Subsequently, W arrington (1984) presented d ata on the reUabfiity and vaUdity of the two tests. The two versions consist of a verbal version in which the subject is presented with words (Recognition Memory Test for Words; RMW), an d a non-verbal version in which the subject is presented with photographs of m en's faces
(Recognition Memory Test for Faces; RMF). In both versions, after presentation the subject is shown the sam e 50 stimuU along with distractor items. The subject's ta sk is to detect the originaUy presented item from the d istracto r item.
Reports in the literature indicate the test is sensitive to unilateral cortical lesions and epileptic disturbance, particularly in the
tem poral regions (LeFever, 1993; W arrington, 1984), although th is is far from conclusive (Hermann et al, 1994).
9.3.2.4. List/Design Learning.
The learning of verbal and non-verbal inform ation w as assessed using the list and design learning paradigm s draw n from the Adult Memory Information and Processing Battery [AMIPB; Coughlan an d Hollows, 1985).
With regard to list learning, the procedure is as follows. A list of fifteen words is read to the subject at the rate of one every second, and the subject is then requested to repeat as m any item s, in any order, as possible. Subsequently, the list is read a furth er four times. After each presentation the subject h a s to attem pt to recall as m any item s as possible. These are then sum m ed (List A1-5 score).
Intrusions are also noted and sum m ed across the five learning trials (List intrusion score). After the final presentation an interference list is read, and recall once again assessed (List B). Finally, the subject is required to recall the originally presented list (List AG). In the non-verbal analogue a sim ilar procedure is adopted. The subject is shown a 9-line drawing for a ten second period, after which it h as to be draw n from memory. Five presentations are given an d both the num ber correct (Design A1-5 score) an d the in tru sio n s (Design intrusion score) are sum m ed. After the fifth presentation the interference drawing is shown, and the num ber of correct fines recorded (Design B). Finally, recall of the originally presented item s is assessed (Design AG).
Given the two forms of presentation, it is thought possible to differentiate between left an d right hem isphere lesions. Studies have indicated th a t the perform ance on te sts of fist/design learning, is m ediated by the hippocam pus where as the recognition memory test may also involve neocortical stru c tu re s (Rausch, 1991).
9 3.2.5. Story Recall
Story recall is designed to assess im m ediate registration of verbal inform ation an d retention over time. This version draw n from the AMIPB (Coughlan and Hollows, 1985) assesses im m ediate recall.
delayed recall (after 30 m inutes) and consequently, percentage retained. The story consists of 2 8 /3 0 item s of inform ation th a t have to be retained. Neuropsychological stu d ies have indicated th a t
dam age to both the cortical temporal, an d hippocam pal regions can im pair perform ance (Rausch, 1991).