Demos and Stimuli
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Causal Perception

Launching and simple non-causal events

There are certain events that we irresistably perceive as causal. The most frequently studied of these is the 'launching' event, seen here.

In this event, the first object (A) appears to 'collide' with the second object (B) and cause it to move, even though they are only geometric shapes on a screen. We see launching even when it is totally implausible, for example if one of the events is a 3D wooden object and the other a circle projected on a screen.

These events do not look causal if there is an offset in either space or time between the end of A's movement and the start of B's movment.

Passing and slipping

If A and B overlap to some degree during the event, it can look like A 'passing' over or through B without making contact. Try the video below, if you don't see passing, watch it again but put it in your peripheral vision.

There is also another type of event called 'slip' events (Rolfs et al., 2013) in which A passes through B and comes out the other side, and then B moves. This is another type of non-causal event, but one in which there are still two moving objects.

Triggering events

If A moves 3x faster than B, the event still looks like a launching event, though it is sometimes called 'braking'

Compare that to when B moves 3x faster than A.

This event is called 'triggering', and in my work I have found that it is treated differently from launching in perception. Triggering seems to involve cases in which B's movement exceeds what should happen when it is struck by A, in other words B looks like it's moving on its own. There are triggering events that don't involve speed, as well.