Perception is required initially, and throughout movement, and is generally used to define characteristics of a movement goal. Thus, in the earliest stages of movement preparation, an error in perceptual judgment might contribute to an overall motor deficit by incorrectly identifying parameters of the movement. Within this chapter, we will review recent research that demonstrates perceptual impairments in PD, and evaluate the impact that this may have on overall motor control.

Deficits early in the movement continuum would likely have observable consequences in the selection of a motor response, and might contribute to an overall deficit in movement initiation. The variable most commonly used to reflect deficits in movement initiation and preparation is ‘reaction time’. Significant impairment on tests of simple reaction time have frequently been demonstrated in PD, and yet there remains some controversy as to whether this impairment may be interpreted as ‘pure’ slowness at the input stage, or whether it represents a delay in the output of a selected motor response to the effector. We will review the evidence establishing the dissociation between motor initiation and stimulus perception in PD.

One of the more interesting controversies in contemporary motor control is something that may be referred to as the ‘movement time paradox’. While it is well known that healthy adults use advance information to prepare a movement (i.e., improve their reaction time), the ability of patients with PD to utilize this advance information has been debated. Historically, research has suggested that PD impairs the ability to utilize advance information. More recent research in this population has suggested, however, that certain stimuli can be used to enhance an individual’s reaction time, but only at the expense of their speed of motor execution (typically measured as ‘movement time’). We discuss this neuropsychological phenomenon, in the context of what it might mean to our understanding of the neurological control of movement.

OBJECTIVES: To seek parents' perceptions and insights pertaining to their preschoolers' screen-viewing behaviors.

METHODS: This qualitative study targeted a heterogeneous sample of parents with children aged 2.5 to 5 years. Two experienced moderators using a semistructured interview guide conducted the ten focus groups between September and November 2003. All focus groups were audio-recorded and transcribed verbatim. In fall 2003 to spring 2004, inductive content analysis was conducted independently by a minimum of two qualitative researchers.

RESULTS: Many parents were not concerned with the amount of screen viewing their children engaged in, although the content of what was on the screen was of particular interest to them. Very few parents seemed to appreciate the linkage between preschoolers' screen-viewing habits and their potential risk for obesity.

CONCLUSIONS: Public health interventions are needed to increase parents' awareness with respect to the harmful effects of excessive screen viewing in preschoolers.

A heterogeneous sample of 65 undergraduate students from the University of Western Ontario (UWO) participated in 13 focus groups. Data collection and analysis took place simultaneously using a combination of the editing and template organizing styles outlined by Miller and Crabtree (1999). Two researchers independently conducted inductive content analysis on each transcript and compared their findings. Many strategies were used to ensure trustworthiness of the data, as outlined by Guba and Lincoln (1989). NVivo software was used to code and categorize emerging themes. The University of Western Ontario Academic Development Fund funded this project and ethical approval was obtained through The University of Western Ontario.