Fig 1.
Experimental layout and target objects.
Bird’s eye view (top), side view (middle) and schematic of the target objects (bottom) for Experiment 1a and 1b (left) Experiment 2 (middle) and Experiment 3 (right). In experiments 1a and 1b the object was grasped with the finger and thumb on either side. In experiment 2 the object was grasped with the thumb on top and finger underneath whist the opposite was the case for Experiment 3. In all cases the starting position was defined by a small (pea-sized) moulded grip on the table top along a sagittal plane (where the plane included the acromion process of the shoulder and the long axis of the object). In Experiment 1a, the target object was placed at one of three horizontal distances from the start point (10cm, 30cm or 50cm). In Experiment 1b it was placed 30cm from the start point. In Experiments 2 and 3 it was placed at one of three horizontal distances from the start point (10cm, 30cm or 50cm) but this time was 15cm above the table top.
Table 1.
Means (and SDs) collapsed across distance for maximum grip aperture (MGA, mm), for all experiments.
Fig 2.
Shows the average movement time (ms), for all participants in reaches to all contact surface sizes (collapsed across distance). The lines represent the finger contact surface (square = small, star = medium, triangle = large). Error bars represent standard error of the mean; these are calculated for within-subjects designs (Cousineau [23], with correction by Morey [24]).
Fig 3.
Shows the average total movement time (ms, solid line), thumb movement time (ms, dashed line), finger movement time (ms, dotted line) for all participants in reaches to all contact surface sizes. The lines represent the finger contact surface (square = small, star = medium, triangle = large). Error bars represent standard error of the mean; these are calculated for within-subjects designs (Cousineau [20] with correction by Morey [21]).
Fig 4.
Shows A) the average total movement time (ms, solid line), B) thumb movement time (ms, dashed line), C) finger movement time (ms, dotted line) for all participants in reaches to all contact surface sizes (collapsed across distance). The lines represent the finger contact surface size (square = small, star = medium, triangle = large). Error bars represent standard error of the mean; these are calculated for within-subjects designs (Cousineau [23] with correction by Morey [24]).
Fig 5.
Shows A) the average total movement time (ms, solid line), B) thumb movement time (ms, dashed line) C) finger movement time (ms, dotted line) for all participants in reaches to all contact surface sizes (collapsed across distance). The lines represent the finger contact surface (square = small, star = medium, triangle = large). Error bars represent standard error of the mean; these are calculated for within-subjects designs (Cousineau [23] with correction by Morey [24]).