Figure 1. Sketch of experimental setup.

(a) Observed (Obs) condition: The cover of the window is open (white bar) and the focal subject (storer, st) caches food in the visual presence of a conspecific (observer). (b) Non-observed (Non) condition: The cover of the window is closed (grey bar) and the focal subject caches food in visual isolation of a conspecific (non-observer). Both observers and non-observers make sounds in the experimental chamber, which are audible to the storer. (c) Peephole (Peep) condition: The cover of the window is closed (grey bar) but one of the two peepholes (small white square) is open; the focal subject caches food in the absence of any behavioural cues, whereas the presence of conspecifics is simulated via playback of sounds recorded from non-observed trials (symbolized by loudspeaker).