Preshaping varies depending on the weight of the object

Abstract

"Preshaping" refers to the action of preparing the shape of fingers when a human reaches out and holds an object. It changes the shape of the finger based on the visual information according to the shape and size of the object in the process from the start of movement to the completion of gripping.

There are many properties of the objects we manipulate, of which the weight can affect Preshaping. However, there is no prior research that examined Preshaping due to differences in weight.

Therefore, this time, preshaping was measured after presenting the subject with information on the difference between two different weights.

The subjects were healthy adults, and were conducted in an environment where visual differences in conditions could be recognized.

Measurement divided weight into two types, and measured the following items to two types of objects. "Time from start of exercise to maximum Forearm supination position", "Time from maximum forearm supination position to grip object", "Maximum abduction distance between thumb and index finger". As a result, when the weight increases, the "time from the start of exercise to the maximum forearm supination position" is reduced, and the "time from the maximum forearm supination position to the grasping target" is extended. Also, the "abduction distance between thumb and index finger" has been expanded. These results indicate that the movement of the forearm changes over time due to the difference in the weight of the object, which is also effective in opening the hand.