Is there a confusion effect in the absence of specialized grouping behavior?
The interactive computer program, implemented as a graphical user interface in Matlab (Mathworks 2004), tasked 88 human subjects with attacking moving tadpole-like objects by clicking on them with the mouse cursor. The start of each screen presentation was signaled by a 3-s text countdown just above the middle of the 142 x 142-mm white clickable arena while the circular mouse cursor was frozen in the exact center. The cursor was then placed under user control, the attack is considered to begin at this point, and a group of tadpoles (each comprising a circular head 1.2-mm diameter and a 3-mm tail) emerged from a randomly chosen side and proceeded across the arena with the tail beating in a swimming fashion at 35.5 mm s-1and off the opposite side of the arena from where they originated. The tadpole group was initialized according to the treatment group (see The 5 Treatments) just outside the bounds of the arena prior to moving into view. A large red arrow was displayed for the first 0.5
