Effects of event rate and display time on sustained attention in hyperactive,normal, and control children

Two experiments were conducted to determine whether hyperactive boys have a unique deficit in sustained attention. Groups with DSM-III diagnoses of attention deficit disorder (ADDH), conduct disorder (CD), ADDH+CD, and learning disorder were compared with normal controls on the Continuous Performance Task. In Experiment 1, stimulus presentation rate (stimulus onset asynchrony, SOA) and display time were varied to manipulate attentional demand, and speed and accuracy of performance were measured. The ADDH group was uniquely affected, with less accurate performance at the fastest and slowest SOA. To distinguish the effects of time on task and SOA, the duration of each SOA condition was held constant in Experiment 2. The poorer performance of the ADDH group at the fastest SOA was no longer evident. This finding indicates that the deficit of sustained attention in boys who have ADDH is associated with a greater susceptibility to refractory effects, which is influenced by practice.This research was supported by the Ontario Mental Health and Ruth Schwartz Foundations through a graduate fellowship awarded to P. Chee and a research grant to R. Schachar, G. Logan, and R. Wachsmuth. Dr. Schachar was also supported by the Canadian Psychiatric Research Foundation. This article is based, in part, on a doctoral dissertation submitted by the first author to the Ontario Institute for Studies in Education. The authors thank Dr. John Lovering and the staff of the Departments of Psychiatry and Psychology, The Hospital for Sick Children, for their cooperation in the conduct of this study. This paper was prepared with the assistance of the Medical Publications Department, The Hospital for Sick Children, Toronto.     

Kommunikative Rhythmen in Gestik und Sprache

Summary. Led by the fundamental role that rhythms apparently play in speech and gestural communication among humans, this study was undertaken to substantiate a biologically motivated model for synchronizing speech and gesture input in human computer interaction. Our approach presents a novel method which conceptualizes a multimodal user interface on the basis of timed agent systems. We use multiple agents for the purpose of polling presemantic information from different sensory channels (speech and hand gestures) and integrating them to multimodal data structures that can be processed by an application system which is again based on agent systems. This article motivates and presents technical work which exploits rhythmic patterns in the development of biologically and cognitively motivated mediator systems between humans and machines. Zusammenfassung. Als Eckpfeiler der natürlichen Verständigung zwischen Menschen sind Gestik und Sprache in der Mensch-Maschine-Kommunikation von großem Interesse. Jedoch gibt es bislang kaum Lösungsvorschläge dafür, wie die multimodalen Äußerungen eines Systemnutzers - als zeitlich gestreute Perzepte auf getrennten Kanälen registriert - in ihrem zeitlichen Zusammenhang zu rekonstruieren sind. In diesem Beitrag wird anhand der Beobachtung, daß menschliches Kommunikationsverhalten von signifikant rhythmischer Natur ist, eine neuartige Methode zur Konzeption eines multimodalen Eingabesystems entworfen. Es basiert auf einem zeitgetakteten Multiagentensystem, mit dem eine präsemantische Integration der Sensordaten von Sprach- und Gesteneingaben in einer multimodalen Eingabedatenstruktur vorgenommen wird. Hiermit werden erste technische Arbeiten beschrieben, die rhythmische Muster für biologisch und kognitiv motivierte Mittlersysteme zwischen Mensch und Maschine ausnutzen.     

Attaining and maintaining preparation: A comparison of attention in hyperactive,normal, and disturbed control children

The hypothesis that hyperactive children have a deficit in sustained attention was investigated. Eighteen children who had attention deficit disorder with hyperactivity (ADDH), aged 7 to 11 years, were compared with children who had conduct disorder (n = 15), mixed conduct disorder and ADDH (n = 26), emotional disorder (n = 18), or learning disability (n = 22), and with normal controls (n = 15). The subjects were tested on three versions of the Continuous Performance Task. Sustained attention was assessed from performance with increasing time on task and from ability to prepare attention in response to a warning. Performance of all subjects deteriorated with increasing time and improved with the opportunity to prepare attention. Hyperactive subjects were not more adversely affected by increasing time, nor did they benefit less than controls from the opportunity to prepare attention. Data reanalysis after rediagnosis according to ICD-9 criteria did not change the results. This study did not confirm the hypothesis that hyperactive children have a unique sustained attention deficit.