The Size-Weight Illusion in Team Lifting

Abstract

The purpose of these studies was to examine whether or not there is a size-weight illusion when participants lift containers as a team. In Experiment 1, teams of participants lifted a set of 16 containers that varied in mass and size and reported their perceptions of heaviness and volume. In Experiment 2, participants lifted the same containers individually. A size-weight illusion was demonstrated in each experiment: Reports of perceived heaviness decreased substantially as the volumes of the containers increased for both styles of lifting. However, both the magnitude of the illusion and mean perceived heaviness were greater in the team lift. Actual or potential applications of this research include the development of safe lifting guidelines for team lifting.

The Effect of Wok Size and Handle Angle on the Maximum Acceptable Weights of Wok Flipping by Male Cooks

“…This phenomenon is very important, because any decrease in perceived heaviness of larger woks could cause the subjects to exceed the limits of safety. This finding was consistent with the previous study of Naylor and Amazeen 26) .…”

“…In other words, the cooks may perceive larger woks to be lighter than smaller woks of the same mass 25) . If this illusion occurs in wok flipping, a larger wok could lead to cooks lifting a greater weight and exceeding their lifting capacity 26) . However, information as to how the size of the wok affects size-weight illusion and flipping capability is still insufficient.…”

The costs of cooperation: Action-specific perception in the context of joint action.

“…These results cannot be easily squared with a strict interpretation of Proffitt's (2006) theory of the economy of action, as it is unlikely that a purely physical account can explain the direction of the found effect. Naylor and Amazeen (2004) have demonstrated that judgments of object heaviness can be greater when lifting with another individual than when lifting alone. However, it does not follow that joint carrying is therefore actually experienced as a more difficult physical task than carrying alone.…”

Box Shape Influences the Size-Weight Illusion During Individual and Team Lifting

“…Also, the stimuli were designed to be larger and heavier than the typical stimuli used in size-weight illusion research, yet not large or heavy enough to approach the limits of safety-estimates of the Lifting Indices for all stimuli in the present experiments were below 1.0. Especially considering the fact that illusion strength can vary across mass (Naylor & Amazeen, 2004), more research would need to be done to determine if the illusion strength was changed at more extreme levels of size and mass. …”