Recados póstumos que reflejan los síntomas de salud mental de los

Inductive reasoning problems were selected because of their similarity to everyday reasoning problems, in that there is usually a number of possible solutions. (Deductive reasoning is different in this respect, problems of this type having a unique correct

solution). Inductive reasoning problems with high g loadings include verbal analogies and series completion and figure analogies and classifications. In an attempt to explore the contributions of language and perceptual skills to reasoning, parallel sets of problems presented in verbal and traditional “non-verbal” format would be required.

The presentation of the tests was an important consideration. Basso and his colleagues in 1973 had stated that “a test purporting to assess the intelligence level of unselected samples of brain-damaged patients should not require responses involving either

verbalization or skilled manipulative activity or subtle differentiation of visuospatial data, although there is probably no intelligence test that fully satisfies these requirements...” It was decided that all words used as stimuli in the verbal forms should be high fi'equency (Thorndike and Lorge, 1936, category A or AA words), to reduce the handicap of aphasia. Similarly, the “non-verbal” forms should be drawn to require the least perceptual and spatial discrimination possible. For example, there should be no answer dependent on counting groups of dots or decisions between similar shapes. In addition the problem and response alternatives should be available for the patient’s inspection, to reduce memory load.

It was decided that a multiple choice format was preferable on several counts. First, it would be less stressful for patients to choose a response, than to have to generate their own answer. This format has been demonstrated to be resistant to affective factors in another neuropsychological test, in this instance of memory function (Coughlan and Hollows, 1986). Secondly, it would allow patients to respond by speaking or pointing. In an extreme example, a patient who was paraplegic could still respond to the verbal forms by having the problem read aloud and then blinking once or twice to indicate “yes’^ or “no” to the alternative answers. Thirdly, it would make scoring relatively simple and

unequivocal, with the potential for future computerisation.

Test items were constructed, according to the principles outlined above, in both verbal and non- verbal format and in three styles of inductive reasoning problem: odd one out,

analogy and series. The correct responses were positioned in a pseudo random way among the response alternatives, so that position preference would confer no advantage on a subject. The aim was to produce six finished tests of twenty five items each, but many more would have to be generated for the pilot study so that sufficient good items could be selected. The number of items that were piloted is given in the Table 1.

format type n format type n

verbal odd one 52 non-verbal odd one 76

analogy 54 analogy 50

series 50 series 35

Table 1. Number of items piloted for each of the six sections of the new test

(ii) ADMINISTRATION OF THE BATTERY

effects of acquired brain damage. The instructions and practice items should be arranged to minimise problems resulting from limited concentration and memory function. For reasons of eflQciency, it was decided that the pilot study could rely on normal subjects filling in a questionnaire alone, with completed examples at the top to explain the task and instructions to guess any item of which they were unsure. Details of the test administration would be rigorously defined for data collection from the experimental series.

(iii) THE TEST SUBJECTS

AGE 18y-40y 40y-54y 55y-69y Male:Female ALL

verbal odd one 22 14 14 14:36 50 analogy 20 19 11 21:29 50 series 20 19 11 24:26 50 non-verbal odd one 18 20 12 19:31 50 analogy 16 18 16 23:27 50 series 18 21 11 16:34 50 TOTALS 114 111 75 117:183 300

Table 2. Age and sex distribution of pilot subjects.

The aim was to pilot each of the six sections on fifty normal people. The majority of subjects were friends and relatives of patients attending the Out Patient Department of the

then National Hospital for Nervous Diseases, Maida Vale. A handful were ambulance crew or nurse escorts. Any subject who did not have time to complete the entire test was

excluded from the sample. The pilot subjects’ responses were monitored throughout data collection. Inspection of the scores of the first nineteen pilot subjects to complete the fifth section, non-verbal analogy, suggested that the items were too diflScult. The section was amended and piloted on a further fifty subjects. The age and sex distribution of the subjects are given above in Table 2.

Inspection of Table 2 reveals that the pilot samples for each section covered a reasonable spread of ages, each age band being represented with approximately similar numbers although with slightly less in the eldest group. There was a sex bias in the pilot sample towards women: 69% females against 31% males. The sex bias was fairly constant across all six tests and across all three age bands. For the purposes of a preliminary examination and grading of items, the slightly skewed sex ratio was not likely to be a confounding factor.

2.2B RESULTS

Each pilot test was carefully examined and twenty five items were selected from each on two criteria:

1. The selected items were valid discriminators. The level of difficulty of each item was calculated from the proportion of pilot subjects responding correctly to it. An item was considered a valid discriminator if it was usually passed by subjects scoring at or above the item’s level of difficulty and usually failed by subjects scoring below the item’s level of difficulty.

2. The pilot subjects’ scores across the twenty five items selected should approximate a normal curve.

The initial selections of twenty five items for each section were made. The distribution of scores from the pilot subjects on these selected items is given in the following six graphs.

Figure 1 Distribution of scores of fifty pilot subjects on the twenty five selected items fi*om each section of the new test.