Subtests

Alertness is the general state of wakefulness that allows a person to react quickly and appropriately to concrete demands. It is the prerequisite for adequate action and represents the basis of every attentional performance - in this respect, alertness is of central importance for participation in road traffic.

This test is designed to assess tonic alertness, which is defined as the ability to maintain a high level of responsiveness in anticipation of a test stimulus. The alertness test measures the simple reaction time in response to a visual stimulus (a cross presented on the monitor).

Sustained attention is not an ability that can be captured by a single type of task. On the contrary, continued maintenance of attention is required in tasks with very different cognitive demands, ranging from simple stimulus detection tasks to tasks with a high cognitive load.

Concentrating on a task is a typical requirement in working life. This involves focusing attention on a mentally demanding activity for a sustained period of time.

In this test, a sequence of stimuli is presented on the monitor. The stimuli vary in a range of feature dimensions: color, shape, size and filling. A target stimulus occurs whenever it corresponds in one or the other of two predetermined stimulus dimensions with the preceding stimulus (e.g. the same shape but with different color, size and filling). In order to adapt the difficulty of the task to the performance level of a subject, different levels of difficulty, that is, reactions to "shape" only or to "color or shape", may be selected.

An intact visual field is an elementary requirement for driving a car. When driving, it is not only necessary to have a view of the entire road in front of the vehicle, but also of the edge of the road and, to a certain extent, of the areas to the left and right of the car. Although the focus is on the traffic in front of the car, it is still necessary to register at the same time if, for example, a pedestrian suddenly steps onto the road or if a shearing vehicle moves sideways towards one's own vehicle.

This task measures the size of the active visual field. The paradigm used requires the detection of a color change in grey circles filling the screen. These critical events appear in different spatial areas and at different distances from the center of the screen. To prevent eye movements to the periphery, a selective visual attention task is also presented centrally.

One important basic attentional function is the ability to maintain attentional focus, extract relevant information and suppress potentially distracting stimulation. Especially the ability to prevent distracting information from triggering one's eye movements towards the distracting stimulus can be conceived as essential in car driving, since the main attentional focus in the center of the visual field should not be triggered by and switched to irrelevant and frequent peripheral stimuli.

This task was developed to measure the ability to maintain a central attentional focus to selectively react to a critical stimulus when distracting visual information is presented. The spatial location as well as the time of presentation of the distractor is unpredictive. The task is explicitly to ignore the distractors and to focus on the centrally presented faces.

The exploration of the visual environment is one of the most basic abilities subserving the safe movement in space, the search for an object, when regarding an object or picture, or in monitoring and controlling a traffic situation. It is a complex process for which the intention and prior knowledge of the individual, the ability to plan ahead, an unrestricted visual field, the ability to shift visual attentional focus, and unimpaired eye movements are important. Equally diverse are the causes of a deficit in exploring the environment after brain damage, which in many cases presents an obvious handicap in daily life.

In this task, a matrix-like arrangement of 5 x 5 stimuli is used, the aim being to detect whether this arrangement includes a critical stimulus or not. One reaction key is used for the answer "present" and another for the answer "not present".

The requirement to explore the matrix on a row-by-row or column-by-column basis permits testing of the ability to shift the required search strategy, which can be impaired, for example, in the case of frontal brain damage.

In everyday life, the capacity to pay attention to several things at once is of great importance. This requires the ability for divided attention to simultaneously ongoing processes.

Deficits of divided attention are frequently diagnosed in neuropsychological practice. The affected patients complain, for example, of difficulties experienced at work when several demands are placed on them simultaneously. In the context of fitness to drive, deficits in divided attention are particularly important, since driving places considerable demands on this attentional function, in view of the large number of actions, some of which occur simultaneously or at least synchronized, and in view of the number of events that must be monitored and observed at the same time.

Divided attention can be tested by means of "dual-task" tasks in which two stimuli have to be paid attention to simultaneously. In this test, this is ensured by a visual and an acoustic task.

Control conditions enable the delineation of modality-specific deficits.

In driving, the ability to allocate the necessary resources at the right time, with the overriding goal of steering the car safely through traffic and reaching the destination on time, is of crucial importance. Driving is characterized by the fact that reactions must be fast and reliably correct, i.e. that the correct reaction to the correct stimulus is made in the shortest possible time and the wrong reaction is suppressed.

This complex test covers several components of attention. It measures aspects of working memory, selective visual attention, inhibition and mental flexibility at an intermediate level of difficulty. The subject sees numbers or letters that are presented in either red or blue color. The task is to selectively respond only to red numbers and blue letters.

Paying attention to specific aspects in our surrounding world is not a static process. On the contrary, it is essentially an active process by which we turn our attention away from objects in order to effectively deal with other objects. In daily life and in the execution of work, it is necessary to gear our attention again and again to newly relevant aspects of a situation. While driving, the execution of a driving maneuver requires the changing orientation of the focus of attention to the individual actions and the adaptation of these to the circumstances and the traffic situation. This requires an efficient internal control of the attentional focus in order to focus on the aspects that are important for the realization of our action goals. In other words, a flexible orientation of the focus of attention is an important prerequisite for behavior that is appropriate to the situation.

This test is a "set shifting" task. A letter and a number are presented simultaneously to the right and left of the center of the screen. The subject has two reaction keys, one on the left and one on the right hand side. The task is to press the reaction key corresponding to the side on which the target stimulus appears. There is a simple condition with the number being the constant target and a complex condition with the target constantly alternating between number and letter, i.e. the subject has to react first to the side of the letter and afterwards to the side of the number and so on. 

An important aspect of behavioral control is the ability to perform an appropriate reaction under time pressure and to simultaneously inhibit an inappropriate behavioral response. The Go/Nogo paradigm was developed to test this form of behavioral control, in which it is important to suppress a reaction triggered by an external stimulus to the benefit of an internally controlled behavioral response. In this paradigm, the focus of attention is directed to predictably occurring stimuli that require a selective reaction, that is, to react or not to react.

Reaction times and errors are recorded in a simple Go/No-go test with two stimuli ""+"" and ""x"", of which only one (the ""x"") is critical.