Visual angle is the critical variable mediating gain-related effects in manual control

Abstract

Theoretically visual gain has been identified as a control variable in models of isometric force. However, visual gain is typically confounded with visual angle and distance, and the relative contribution of visual gain, distance, and angle to the control of force remains unclear. This study manipulated visual gain, distance, and angle in three experiments to examine the visual information properties used to regulate the control of a constant level of isometric force. Young adults performed a flexion motion of the index finger of the dominant hand in 20 s trials under a range of parameter values of the three visual variables. The findings demonstrate that the amount and structure of the force fluctuations were organized around the variable of visual angle, rather than gain or distance. Furthermore, the amount and structure of the force fluctuations changed considerably up to 1°, with little change higher than a 1° visual angle. Visual angle is the critical informational variable for the visuomotor system during the control of isometric force.

Compensatory properties of visual information in the control of isometric force

“…Here, it has been shown that enhancement of gain (pixel/Newton ratio; p/N) up to some level improves performance beyond which the performer cannot take advantage of the more precise information, and may even lead to a performance decrement (Newell & McDonald, 1994). The findings from these studies suggest that there is some optimal level of gain for the experimental conditions that more generally can be interpreted as an effect of visual angle, because viewing distance is constant in most studies of gain (Vaillancourt, Haibach, & Newell, 2006). This inverted-U pattern of findings for performance and visual gain parallels that for the effect of the precision of knowledge of results (KR) on discrete response outcome (Newell & Kennedy, 1978;Rogers, 1974).…”

Spatiotemporal dynamics of brain activity during the transition from visually guided to memory-guided force control

“…The low and high visual gain levels correspond to visual angles of 0.026°and 2.908°. The selected visual gains were well below and above 1°, spanning the range across which a dramatic change in force performance will occur (Coombes et al 2010;Vaillancourt et al 2006). The two levels of visual gain will be referred to as low gain (0.026°) and high gain (2.908°) throughout the remainder of this article.…”

Effects of STN DBS on Rigidity in Parkinson's Disease

“…A high control-to-display visual feedback gain level was used for this task, which meant that small changes in the amount of force produced caused large fluctuations in cursor movement. This visual feedback setup ensured that subjects had to attend to the display computer monitor in order to maintain the cursor at the target [37].…”