W. Sturm © SCHUHFRIED GmbH
Assessment of sub-functions of attention, suitable for respondents from the age of 7.
Modern views of the dimensionality of attention can be summarized by the model proposed by van Zomeren and Brouwer (1994). According to this model the central factors include the distinguishing of intensity and selectivity aspects of attention; these need to be differentiated into their more specific components. The intensity aspect of attention comprises two components, alertness and vigilance; alertness involves the short- and longer-term arousal of attention, while vigilance relates to the sustaining of this arousal. With regard to the selectivity aspect of attention processes the model distinguishes between focused or selective attention and divided attention. The spatial orienting of attention is a separate, additional dimension (Posner et al., 1978, 1984). It does not form part of the model described above but is included in more recent taxonomies (Sturm, 2005). Both Posner and Raichle (1994) and Fernandez-Duque and Posner (2001) distinguish three types of attention networks: a) Orienting (corresponds to the network of spatial direction of attention), b) Vigilance (corresponds to the intensity dimension) and c) Executive Attention (corresponds roughly to the selectivity dimension).
The WAF test battery consists of six tests that can be administered independently of each other or, as a test battery, in any desired combination. In addition, WAFW can be used to make a differential assessment of sensory impairments.
- WAFW: Pre-tests for attention functions
- WAFA: Alertness
- WAFV: Vigilance / sustained attention
- WAFS: Selective attention
- WAFF: Focused attention
- WAFG: Divided attention
- WAFR: Spatial attention and visual field / extinction – neglect
For each of the WAF tests different test forms are available, enabling dimensions of attention to be assessed under different presentation modalities. There are thus separate sub-tests for visual, auditory and crossmodal presentation. In some subtests of the WAF test battery automated and controlled aspects of attention are measured separately; the stimuli either become more prominent because the intensity level is increased (”popping out”), or they become less prominent because their intensity is decreased and cognitively controlled ”top down” processes are then required. Both attention processes are relevant in everyday life; both can interact and both can be selectively impaired, for example as a result of brain damage, since they are based on different cerebral networks (Corbetta & Schulman, 2002).
In order to exclude the possibility that perceptual impairments may influence the processing of the stimuli used in WAF, thus impeding reliable diagnosis, WAFW can be used before the start of an assessment in order to determine whether the respondent has the perceptual ability necessary for completion of the WAF tests. 4 test forms: Separate forms for distinguishing brightness, distinguishing shape, distinguishing pitch and distinguishing volume.
WAFA measures reaction time in response to simple visual or auditory stimulus material. The stimulus is presented either with or without a warning signal in the same stimulus modality or the contrasting one (intrinsic vs. phasic alertness). A special standardization process enables fatigue or stress parameters to be measured. 2 test forms (standard form and short form), each with 6 subtests: Subtests: Intrinsic (visual), phasic (unimodal visual), phasic (crossmodal visual/auditory), intrinsic (auditory), phasic (unimodal auditory), phasic (crossmodal auditory/visual).
In WAFV the respondent is presented with visual and auditory stimuli that occasionally diminish somewhat in intensity. The person’s task is to respond to these occasional cases; when sustained attention is being measured they constitute around 25 % of the stimuli while in the case of vigilance they make up some 5 % of the stimuli. 8 test forms (4 long and 4 short forms; the short forms for sustained attention have been specially developed for children and young people): Separate forms for vigilance (visual), vigilance (auditory), sustained attention (visual), sustained attention (auditory) Separate short forms for sustained attention (visual) and sustained attention (auditory).
The spatial orienting of attention is measured using either 4 or 8 spatial positions in a task similar to a Posner paradigm. Peripheral (exogenous) and central (endogenous) spatial cues are used. In the neglect test stimuli are presented at various positions in the right or left visual field or simultaneously in equivalent positions in both halves of the field of vision (extinction condition). 5 subtests: Subtests with either four or eight stimulus positions and peripheral or central cues. In addition a test for visual field / neglect under extinction conditions.
The respondent is presented - depending on the subtest – with relevant visual or auditory stimuli against a background of distracting stimuli. The person’s task is to respond when two predefined changes in relevant stimuli occur consecutively; all other stimuli are to be ignored. 3 subtests: Unimodal (visual), unimodal (auditory), crossmodal.
The person receives relevant and irrelevant stimuli in one or both presentation modalities; the task is to react to changes in the relevant stimuli while ignoring irrelevant ones. 3 subtests: Unimodal (visual), unimodal (auditory), crossmodal.
The respondent receives stimuli on two visual channels or on one visual one and one auditory one. The task is to monitor both channels to determine whether one of the stimuli changes twice in succession. 2 test forms (standard form and short form), each with 2 subtests: Subtests: unimodal (visual), crossmodal.
In all WAF tests the reaction times and the various error types are scored. For most of the variables a norm comparison is also carried out, yielding percentile ranks and T scores.
Especially given the short testing time, the reliabilities (Cronbach’s alpha) obtained for the WAF tests are very good.
depending on test form and subtest between r=0.86 and r=0.98 (children and young people 0.92–0.97)
depending on test form between r=0.92 and r=0.99 (children and young people 0.96–0.97)
depending on test form between r=0.88 and r=0.97 (children and young people 0.92–0.94)
depending on subtest between r=0.93 and r=0.97 (children and young people 0.91–0.96)
depending on subtest between r=0.94 and r=0.97 (children and young people 0.93–0.94)
depending on test form and subtest between r=0.89 and r=0.97 (children and young people 0.96)
A study of the tests’ construct validity involving a sample of n=256 adult respondents and 270 children and young people provided empirical confirmation of the theoretical model on which the WAF test battery is based and was able to distinguish it from other models.
For all WAF tests norms representative of the general population are available; the norms relate to N=295 individuals in the age range 16–77. The norms are available both for the sample as a whole and also separated according to educational level. In addition, all WAF tests provide raw scores adjusted for age effects for the main variables; this is a particularly efficient method of standardization for age. A norm sample of N=270 children and young people in the age range 7–17 is also available. Some norms representative of the general population consisting of N=309 or N=313 individuals aged between 16 and 80 are available for individual subtests of the short forms of WAFG and WAFA. ## Time required for the test The time required to complete the individual WAF tests is relatively short. It is therefore possible to create batteries of tests for complex assessment purposes without requiring too much of the respondent in terms of time or motivational commitment. It is usually not necessary to administer each test in all stimulus modalities. This must be decided by the user, taking into account any information about a patient’s difficulties or disabilities that has already been gathered. The test results cannot be interpreted with confidence unless the person/patient meets the sensory and motor requirements for satisfactory completion of the test.
- WAFW: approx. 2 minutes for each pre-test
- WAFA: between 14 and 27 minutes, depending on test form
- WAFV: between 15 and 30 minutes, depending on test form
- WAFR: approx. 5 minutes for each test form
- WAFF: approx. 10 minutes for each subtest
- WAFS: approx. 8 minutes for each subtest
- WAFG: between 12 and 30 minutes, depending on test form
A standard USB headset is required for administration of the auditory and crossmodal subtests of the WAF tests.