Dynamic size-weight changes after object lifting reduce the size-weight illusion

In the size-weight illusion, the smaller object from two equally weighted objects is typically judged as being heavier. One explanation is that the mismatch between the weight expectation based on object size and actual sensory feedback influences heaviness perception. In most studies, the size of an object is perceived before its weight. We investigated whether size changes would influence weight judgement if both would be perceived simultaneously. We used virtual reality to change the size and weight of an object after lifting and asked participants to judge whether the object became lighter or heavier. We found that simultaneous size-weight changes greatly reduced the size-weight illusion to perceptual biases below discrimination thresholds. In a control experiment in which we used a standard size-weight illusion protocol with sequential lifts of small and large objects in the same virtual reality setup, we found a larger, typical perceptual bias. These results show that the size-weight illusion is smaller when size and weight information is perceived simultaneously. This provides support for the prediction mismatch theory explaining the size-weight illusion. The comparison between perceived and expected weight during the lifting phase could be a critical brain mechanism for mediating the size-weight illusion.

Dynamic Size-Weight Changes After Object Lifting Reduce the Size-Weight Illusion

ABSTRACTIn the size-weight illusion, the smaller object from two equally weighted objects is typically perceived as being heavier. One explanation is that the mismatch between the weight expectation based on object size and actual sensory feedback influences heaviness perception. In most studies, the size of an object is perceived before its weight. We investigated whether size changes would influence weight perception if both would be perceived simultaneously. We used virtual reality to change the size and weight of an object after lifting and asked participants to judge whether objects became lighter or heavier. We found that simultaneous size-weight changes greatly reduced the size-weight illusion to perceptual biases below discrimination thresholds. In a control experiment in which we used a standard size-weight illusion protocol with sequential lifts of small and large objects in the same virtual reality setup, we found a larger, typical perceptual bias. These results show that the size-weight illusion is smaller when size and weight information is perceived simultaneously. This provides support for the prediction mismatch theory explaining the size-weight illusion. Furthermore, these findings suggest that the lifting phase is a critical time window during which brain mechanisms comparing perceived and expected weight mediate the size-weight illusion.

A Test of Soccer Cleats Compared to Football Cleats during Football Speed and Agility Drills: Do Soccer Cleats Make You Faster or More Agile?

Background: Football players have many options in cleat styles and designs today. Skill position players especially may opt for soccer cleats over football cleats in the belief that the soccer cleats will help them run faster. Purpose: The purpose of this study was to compare soccer cleats to football cleats during common American football field drills. Methods: Sixteen young adult males performed a circuit of four American football speed and agility drills (forty yd-dash, ladder drill, 5-10-5-drill, and six-route route tree) in both soccer and football cleats. Performance measures (such as time or steps) were recorded for each drill. Subjects were asked to score the shoes in terms of comfort, heaviness, stability, and traction at various times. Results: Two significant differences were found as a result of this study. Out route times (seconds) were significantly different between football cleats and soccer cleats. The other significant difference occurred in the perceived heaviness of each cleat. Conclusion: This study found minimal difference between football and soccer cleats in performance and perception. Participants in this study showed split preferences as to which cleat was better for performance. Of four studied perceptual outcomes, only the heaviness perception was significantly different. This was further backed by performance data that had only one significant difference among seventeen performance-associated measurements.

Lowering Objects with a Power Assist Robot: The Preliminary Study

We developed a 1-DOF power assist robot to lower objects from higher position to lower position. Subjects lowered objects of different sizes with the robot and we analyzed heaviness perception, load force, motions (displacement, velocity, acceleration) etc. We determined a psychophysical relationship between actual heaviness and perceived heaviness for objects lowered with the robot system. We tried to identify some control parameters from the analytical results, and proposed them to be used to determine and develop an appropriate control scheme for power assist robots for lowering heavy objects in various industries. This paper reports the preliminary study results on this issue.