Simple motor actions like moving marbles upward or downward between two cardboard boxes might seem meaningless to many. But a new study shows that such actions can partly determine people's emotional memories or help recall their good or bad times.

Moving marbles upward caused participants to recall sunnier experiences, and moving them downward had the opposite effect, says Daniel Casasanto (Max Planck Institute and Donders Institute, Nijmegen) and Katinka Dijkstra (Erasmus University, Rotterdam).

When people talk about positive and negative emotions, they often use spatial metaphors. For instance, a happy person is on top of the world but a sad person is down in the dumps.

To test this link between vertical space and emotion, Casasanto and Dijkstra asked students to move glass marbles upward or downward into one of two cardboard boxes, with both hands simultaneously, timed by a metronome.

Meanwhile, they had to recount autobiographical memories with either positive or negative emotional valence, like 'Tell me about a time when you felt proud of yourself', or 'a time when you felt ashamed of yourself.'

When prompted to tell positive memories, participants began recounting their experiences faster during upward movements, but when prompted to tell negative memories they responded faster during downward movements.

Memory retrieval was most efficient when participants' motions matched the spatial directions that metaphors in language associate with positive and negative emotions.

The second experiment tested whether these seemingly meaningless motor actions could influence the content of people's memories.

Participants were given prompts, like 'Tell me about something that happened during high school,' so they could choose to retell something happy or sad.

Their choices were determined, in part, by the direction in which they were assigned to move marbles, says a release from the Donders Institute and Erasmus University, Holland.

Moving marbles upward encouraged students to recount positive high school experiences like 'winning an award,' but moving them downward to recall negative experiences like 'failing a test.'

The findings are slated for publication in April edition of Cognition.