Do Pigeons (and us) Perceive Time Logarithmically

There are asymmetries in the way animals perceive numbers and time, and a recent experiment showed that pigeons underestimate the midpoint between two time intervals.
In the experiment, pigeons were trained to tap one lever when a light flash was "short", perhaps 1 second long, and another lever when the flash was "long", say 16 seconds. When the birds then saw flashes of intermediate length, you would expect them to distinguish long from short around the mid-point of 8 or 9 seconds. But instead they switched at 4 seconds.