Técnicas e Instrumentos de Recogida de Datos

The global nature of orientation and attention functions implies likely impairment from neurological damage (Lezak, 1 995). While the two functions are interrelated, and often assessed together, orientation can remain intact when attentional deficits are mild. Attentional deficits, in particular, tend to persist well after other signs of neurological damage have been overcome (Walsh, 1 994). Measurement of both functions appear closely related to the driving task.

O rientation. Orientation is defined as an awareness of self in relation to one's surroundings, which requires "consistent and reliable integration of attention, perception and memory" (Lezak, 1 995, p.335). Impaired awareness for time and place is most common, and is reliant on "both continuity of awareness and the translation of immediate experience into memories of sufficient duration to maintain awareness of one's ongoing history" (Lezak, 1 995, p.335). Orientation, therefore, is also c losely related to the ability to retain information, but not necessarily the ability to verbalise it. Tests of mental status typically assess orientation for time, place and person, in a very general sense. Other tests , however, are available to measure more specific components of orientation. For driving, measurement of orientation is relevant to one's sense of place, direction, and distance. Drivers must be aware of their own orientation in space and possess the ability to relate to the position, direction, or movement of other objects (spatial orientation). Unfortunately, there are no formal neuropsychological tests which measure spatial orientation in a traffic environment. Aspects of spatial orientation are, however, represented in some tests of visual perception, such as Judgement of Line Orientation, the Benton Visual Retention Test-Revised, the Tactual Performance Test, and the Rey-Osterrieth Complex Figure . While it is difficult to determine how total scores reflect an orientation component, each of these tests have demonstrated a significant relationship with various measures of practical driving outcome in neuropsychologically-impaired subjects (Brooke et al., 1 992; Galski et al.,

1 993; Priddy et al., 1 990; Rothke, 1 989; van Wolffelaar et al., 1 988).

orientation. Topographical orientation is critical for driving, and involves memory for familiar routes and directional sense. Here, impairment may result in reduced ability for revisualisation or "the retrieval of established visuospatial

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knowledge " ( Lezak, 1 995, p.348). Anecdotal evidence from neuropsychologically­ impaired driver studies reveals that some subjects are unable to retrace familiar routes, and may easily become disoriented when driving home from places they regularly freq uent ( Friedland et al., 1 98 8 ; Lucas-Blaustein et al., 1 98 8 ) . As part of topographical orientation, directional sense demands an ability to perform mental spatial rotations, and also incorporates left-right orientation. Confusion with the latter is often apparent following left hemisphere damage (Lezak, 1 995).

Measurement of topographical orientation is not common in neuropsychological assessment, and subsequently there are few formal measures available (Walsh, 1 994 ) . The most closely related tests are those which measure route finding. Simm's ( 1 985a, 1 985b, 1 986, 1 987, 1 989) inclusion of the Standardised Road Map Test of Direction Sense ( Money, 1 976), as part of an assessment programme for individuals with physical and neuropsychological impairment, is therefore an important contribution to the I iterature. The test involves subject's describing an hypothetical journey as it is traced along a pathway by the examiner. Results indicated, that for the majority of studies conducted on neuropsychologically-impaired subjects, the Standardised Road Map Test of Direction Sense was significantly related to in-car assessment ratings. A functional sense of time, especially time estimation, is also related to the concept of orientation and is often impaired through neurological damage ( Lezak, 1 995). Again, there is are a lack of formal assessment methods, although the problem is usually overcome by simply asking the subject relevant questions. Although a sense of time would seem important for strategic levels of the driving task, such as planning to arrive at a certain destination in time, this has not been addressed in the neuropsychologically­ i mpaired driver research.

Attention. Compared with orientation, the concept of attention is difficult to define in the context of driving, and must be monitored indirectly through other aspects of behaviour for which there is an attentional component (van Zomeren et al., 1 985). Distracted attention, or impaired focused behaviours, for example, are typical deficits of attention. However, at a higher level, a definition of attention is difficult to separate from concentration and tracking, which affects the ability to maintain continued focus on problem solving or following a sequence of ideas (Lezak, 1 995).

COGNITIVE MEASURES

Distracted attention, or impaired focused behaviours, can be assessed through a variety of tests which measure vigilance or the ability to sustain and focus attention. The most common tests, however, monitor performance on simultaneous tasks such as item cancellation, where the subject must attend to one thing and not others. Here, a high error rate may reflect attentional disorder. However, as these tests involve a timed component, it is difficult to separate out the associated effects of speed of information processing (Lezak, 1 995). Series of reaction time trials may also be used to complement other measures of attention. In addition, tests of short term storage capacity (e.g. digit span and tests of repetition), may be used on the principle that they examine how fast and how much the attentional system can handle.

At the higher level, assessment of attention focuses on complex mental operations involving divided or shifted attention, which relate closely to the executive functions. Measurement of attention alone is even more difficult at this level, where problems with separating out speed of complex information processing and tracking capacity are apparent (Uomoto, 1 990). Neuropsychological tests such as the Stroop Colour Word Test, Paced Auditory Serial Addition Test (PASA T), Trail making A and B , and versions of the Symbol Digit test, are typically used to assess aspects of complex attention (Lezak, 1 995; Walsh, 1 994 ). However, caution must be given to other interpretations that can be attributed to poor performance on these tests, such as selective attention deficit and other problems with complex attention.

Tests which measure vigilance have not shown a clear relationship with outcome on practical driving measures for neuropsychologically-impaired driver subjects. Single factor studies have found that Letter Cancellation tasks bear no relation to driving test results (Hartje et al., 1 992; Galski et al., 1 993). However, multiple regression analyses have found that this same test was one of four significant predictors of driving outcome (Galski et al. , 1 990). While the correlation coefficient was quite low, it is interesting that one of the other significant predictors was an observed rating of inattention measured during actual driving. Results of simple paced tests, such as digit span, have also shown variable results, and are more likely to differentiate neuropsychologically-impaired subjects from controls than relate to any measure of practical driving (Quigley & DeLisa, 1 983; Retchin et al. , 1 988; Sivak et al. , 1 98 1 ) . The results of simple reaction time tests are also variable, and are less able t o predict driving outcome than higher level choice or complex reaction time measures (Galski et

al. , 1 993 ; Golper et al. , 1 980; Hartje et al. , 1 992; Madeley et al., 1 990; van Zomeren et al., 1 98 8 ) .

Despite some uncertain test results, vigilance to the driving task i s clearly important. Abi lity to sustain attention has been stressed as an issue for neuropsychologically­ impaired drivers, especially when driving at night, or long distance over similar terrain. Here, a reduction in attention span, and an increase in the likelihood of becoming more easily fatigued, are seen as potential problems, which are difficult to assess objectively. Interestingly, evidence for possible reduction in attention span of neuropsychologically­ impaired drivers has been noted from practical driving assessments of longer duration. Interestingly, Sivak et al. ( 1 98 1 ) found that sustained attention, as measured by Porteus Maze Test scores, was significantly related to the driving quality of control subjects. The same result was not true of neuropsychologically-impaired subjects, although this group also demonstrated increased variability in individual test scores.

attention. The ability to operate at, and sustain, a level of complex attention is also an integral part of the driving process. Traffic conditions require constant monitoring and responding to information from multiple sources within a dynamic environment. One of the biggest questions faced by assessors is to decide whether neuropsychologically-impaired drivers can deal with such complexity.

Neuropsychological tests which include an element of complex attention typically find significant di fferences between neuropsychologically-impaired drivers and controls ( Katz et al . , 1 990; Sivak et al., 1 984; van Zomeren et al. , 1 988). Fewer tests have actually been compared with real diving criteria. Here, unclear results have been shown for the well known Stroop Colour Word Test, which can reflect difficulty concentrating, warding off distractions, and ability to shift attention (Friedland et al., 1 989; van Zomeren et al . , 1 988). Other tests requiring focused concentration and ability to shift, such as Trailmaking A and B, are significantly related to some driving criteria, specifically, tracking a constant path in traffic, which has a high complex visual search component (van Zomeren et al. , 1 988). Some interesting results have also been shown for the Symbol Digit modalities test. Gouvier et al. ( 1 989) administered both oral and written versions and found that the oral test significantly predicted driving outcome assessed over a closed course. In one of several studies by Galski et al. ( 1 993 ). the Digit Symbol subtest of the W AIS-R was found to relate significantly with driving test outcome.

COGNITIVE MEASURES

Anecdotal evidence from research on neuropsychologically-impaired drivers suggests problems with inattention and ability shifting to attend to more than one stimulus at the same time. For instance, there are numerous accounts of difficulties attending to busy traffic, where amount and timing of responses to the driving situation become crucial ( van Zomeren et al., 1 987). Incidents of frequent inattentiveness to traffic signs and even total breaks in attention, where subjects proceeded to do other things without apparent concern for the driving task, are also examples from the literature (Quigley & DeLisa, 1 983).