Re: Ambiguous figures
[From Rick Marken (2004.05.07.1350)]
Martin Taylor (2004.05.07.14:03)–
No. Each box represents 9 continuous minutes of viewing, but for the
statistics that are displayed, the time is reset to zero at each
switch of the percept. To be concrete, let’s imagine a small segment
of those 9 minutes, during which the following events occurred (B =
switch into Bubble, D = switch into Dent, numbers = seconds between
events).
B 2.0 D 1.3 B 5.2 D 0.5 B 3.1 D 2.6 B …
The diagram would start at {0, 1} {time, probability that no switch
has yet occurred). For the “switch out of bubbles” curve, at time
2.0 it would drop to {2.0, 2/3} since on 2/3 of the occasions when
Bubbles were being seen, no switch to dent had occurred.
You lost me. Where did the 2/3 probability come from? All I see is that a trial starts out with a person saying that they see bubbles (B). Then 2 seconds later the person says that they see dents (D). How does this translate to a 2/3 probability of switching out of the perception of “bubbles” after 2.0 seconds?
At time 3.1
it would drop to {3.1, 1/3}, and at 5.2 it would drop to {5.2, 0}.
Where does time 3.1 come from? Doesn’t the first switch back to bubbles (B) occur after 3.3 seconds? And, again, how is the 1/3 probability calculated?
Maybe I missed it but could you explain what the participants were actually doing in this experiment? Were the subjects asked to fixate on a single point in the display? It seems like eye movements, leading to new views of the image, would have a lot to do with when (and whether) there was a perceptual shift. When I want to go from seeing the “wife” to seeing the “witch” in the well known “wife/witch” figure (reproduced in my “Looking at behavior through control theory glasses” paper) it seems to me that I scan over the image a bit to foveate new features of the image.
Best regards
Rick