Klaus Willmes

On the Development of the Mental Number Line: More, Less, or Never Holistic with Increasing Age?.

Magnitude is assumed to be represented along a holistic mental number line in adults. However, the authors recently observed a unit-decade compatibility effect for 2-digit numbers that is inconsistent with this holisticness assumption (H.-C. Nuerk, U. Weger, & K. Willmes, 2001). This study used the compatibility effect to examine whether the mental number line representation of magnitude changes toward greater or less holisticness in children from Grades 2-5. The results indicate that decades and units of 2-digit numbers are processed separately rather than holistically from Grade 2 on. However, this separate processing seems to develop from a more sequential (left-to-right) to a more parallel processing mode. Moreover, children may use different strategies depending on task demands. The results are interpreted in the framework of Sieglers overlapping waves model.

Efficacy of a reaction training on various attentional and cognitive functions in stroke patients

Abstract The efficacy of a computer-assisted reaction training on various attentional and cognitive functions was studied in stroke patients with lateralised cortical lesions. Patients were tested three times with a comprehensive test battery comprising several attention tests, as well as more general cognitive tasks, with the aim of separating training effects from spontaneous recovery and trivial practice effects. An additional follow-up assessment—carried out 6 weeks after the end of training—was employed to examine the stability of training effects. At baseline the right-hemisphere-damaged patients showed more pronounced impairments of sustained attention and vigilance, whereas the left-brain-damaged patients performed worse in choice reaction tasks, making more false-positive responses. Both groups showed significant training effects for a number of attention functions, but not for vigilance, and there was no generalisation of the training effects to more general cognitive functions. Overall, the tra...

Hemispheric Asymmetry in the Recognition of Emotional Attitude Conveyed by Facial Expression, Prosody and Propositional Speech

In this study 27 patients with right hemisphere lesions, 25 patients with left hemisphere lesions and 26 normal control subjects were investigated for unimodal and simultaneous multimodal recognition of emotional attitude. All subjects were shown 330 videotaped items of 4 seconds duration, each of which was to be judged in terms of facial expression, emotional prosody and the emotional meaning of the underlying spoken sentence. In a preceding experiment comparable unimodal emotional stimuli were applied. The results suggest (a) right hemisphere superiority for recognition of emotions conveyed by facial and prosodic information, (b) a right hemisphere dominance for the recognition of fear and (c) no significant enhancement of right hemisphere superiority under multimodal presentation of emotional stimuli.

Prepairs and repairs: different monitoring functions in aphasic language production.

Picture descriptions of aphasic patients and nonaphasic controls were analyzed with respect to type and amount of linguistic repairs and searching phenomena (prepairs). Repairs occurred far less frequently than prepairs, which indicates impaired postarticulatory as opposed to intact prearticulatory monitoring. Prepairs were found to be most frequent in patients with relatively good comprehension, in patients with poor production, and in those who had both good comprehension and poor production. Contrary to expectation, there was no reliable difference in the distribution of prepairs and repairs between patients with Wernickes and Brocas aphasia, although these two groups differed in performance. Possible mechanisms of linguistic monitoring are discussed.

Is there a generalized right hemisphere dominance for mediating cerebral activation evidence from a choice reaction experiment with lateralized simple warning stimuli

The influence of simple lateralized visual warning stimuli on decision and movement time (jump reaction) for a centrally presented choice reaction stimulus was examined in 20 normal healthy subjects. Without warning the right hand (left hemisphere) showed faster decision times for the choice reaction stimuli. After presentation of the lateralized warning stimulus this difference was no longer present while for both hands there was improvement after warning. This indicates that the left hand (right hemisphere) showed a more pronounced improvement of decision time following the warning stimulus than the right hand. In contrast, the number of errors (false positives) increased after LVF stimulation. Experimental conditions had no influence on movement time at all. It was concluded that the complexity of the lateralized warning stimulus and not of the centrally presented reaction stimulus determines hemispheric activation dominance.

Facet theory applied to the construction and validation of the Aachen Aphasia Test

The linguistic performance of 120 aphasic patients of the four standard syndromes assessed by the Aachen Aphasia Test (AAT) is analyzed by a nonmetric (ordinal) multidimensional scaling procedure (Smallest Space Analysis, SSA1). The linguistic structure of the test items is characterized within the framework of L. Guttmans facet theory. Three systematic components (facets) are discerned: linguistic modality, unit, and regularity. Properties of the facets as well as their relations are assessed and tested empirically by analyzing the interrelations among different items or sets of items. The spatial configurations obtained by the scaling procedure fit only partially the expectations derived from the facet-theory model. The modality facet was found to have a strong overriding influence on the aphasic test performance. The facets unit and regularity were only found for the most rigorously designed subtests. Written Language and Comprehension. The results suggest the introduction of a new combined facet linguistic complexity which reflects the dependency of the facets regularity and unit.

Approaches to Aphasia Therapy in Aachen

Our experience with aphasia therapy has developed in the Neurology Department of the Technical University in Aachen under the direction of Klaus Poeck. Aphasia therapy is provided for both in- and outpatients. Inpatients stay either on acute wards, including intensive care, or on a special aphasia ward. Outpatients are seen either for extensive neurolinguistic and neuropsychological diagnosis at the neurological clinic or for aphasia therapy administered at the school of logopedics. The aphasia therapists cooperate with an interdisciplinary group of researchers including linguists, psychologists, and neurologists. Research on therapy has developed from clinical, diagnostic, and theoretical interests. In the past, we have made several attempts to combine different approaches to a comprehensive treatment regimen (cf. Huber, 1988; Huber, 1991, 1992; Huber, Poeck, & Springer, 1991; Huber & Springer, 1989; Poeck, 1982; Poeck, Huber, Stachowiak, & Weniger, 1977; Springer, 1986; Springer & Weniger, 1980; Weniger,Huber, Stachowiak, & Poeck, 1980; Weniger & Springer, 1989). Furthermore, we have been concerned with methodological issues of therapy research using either single case or group designs (Willmes, 1985, 1990).

Lactate as a diagnostic marker in transient loss of consciousness

PURPOSEnThe diagnostic classification of disorders of consciousness is often challenging, particularly the distinction between epileptic and non-epileptic seizures. The aim of the study was to examine serum lactate as a diagnostic marker of transient loss of consciousness.nnnMETHODnSerum lactate levels in blood samples drawn within 2h of the event were compared retrospectively between patients with generalized tonic-clonic seizures (n=195) and patients with other seizures (syncopes [n=52], psychogenic non-epileptic seizures [n=17], and complex focal seizures [n=37]), respectively.nnnRESULTSnSerum lactate in patients with generalized tonic-clonic seizures was significantly (p<0.001, Mann-Whitney-U test) increased in comparison to other forms of seizure incidences. The area under the ROC-curve was 0.94 (95% CI 0.91-0.96). For a cut-off concentration of 2.45mmol/l, the sensitivity was 0.88 and the specificity 0.87.nnnCONCLUSIONSnSerum lactate levels in the acute diagnosis were an excellent biomarker for the discrimination of generalized seizures from psychogenic non-epileptic and syncopal events, corroborating its importance for the standard work-up of acute disturbances of consciousness.

The contribution of phonation type to the perception of vocal emotions in German: an articulatory synthesis study.

Vocal emotions are signaled by specific patterns of prosodic parameters, most notably pitch, phone duration, intensity, and phonation type. Phonation type was so far the least accessible parameter in emotion research, because it was difficult to extract from speech signals and difficult to manipulate in natural or synthetic speech. The present study built on recent advances in articulatory speech synthesis to exclusively control phonation type in re-synthesized German sentences spoken with seven different emotions. The goal was to find out to what extent the sole change of phonation type affects the perception of these emotions. Therefore, portrayed emotional utterances were re-synthesized with their original phonation type, as well as with each purely breathy, modal, and pressed phonation, and then rated by listeners with respect to the perceived emotions. Highly significant effects of phonation type on the recognition rates of the original emotions were found, except for disgust. While fear, anger, and the neutral emotion require specific phonation types for correct perception, sadness, happiness, boredom, and disgust primarily rely on other prosodic parameters. These results can help to improve the expression of emotions in synthesized speech and facilitate the robust automatic recognition of vocal emotions.

A Systematic Investigation of Accuracy and Response Time Based Measures Used to Index ANS Acuity.

The approximate number system (ANS) was proposed to be a building block for later mathematical abilities. Several measures have been used interchangeably to assess ANS acuity. Some of these measures were based on accuracy data, whereas others relied on response time (RT) data or combined accuracy and RT data. Previous studies challenged the view that all these measures can be used interchangeably, because low correlations between some of the measures had been observed. These low correlations might be due to poor reliability of some of the measures, since the majority of these measures are mathematically related. Here we systematically investigated the relationship between common ANS measures while avoiding the potential confound of poor reliability. Our first experiment revealed high correlations between all accuracy based measures supporting the assumption that all of them can be used interchangeably. In contrast, not all RT based measures were highly correlated. Additionally, our results revealed a speed-accuracy trade-off. Thus, accuracy and RT based measures provided conflicting conclusions regarding ANS acuity. Therefore, we investigated in two further experiments which type of measure (accuracy or RT) is more informative about the underlying ANS acuity, depending on participants’ preferences for accuracy or speed. To this end, we manipulated participants’ preferences for accuracy or speed both explicitly using different task instructions and implicitly varying presentation duration. Accuracy based measures were more informative about the underlying ANS acuity than RT based measures. Moreover, the influence of the underlying representations on accuracy data was more pronounced when participants preferred accuracy over speed after the accuracy instruction as well as for long or unlimited presentation durations. Implications regarding the diffusion model as a theoretical framework of dot comparison as well as regarding the relationship between ANS acuity and math performance are discussed.