Pdiso8a

The monkeys were tested using the Language Research Center’s Computerized Test System comprising a personal computer, digital joystick, color monitor, and pellet dispenser (Evans et al., 2008 ; Richardson et al., 1990 ). Monkeys manipulated the joystick with their hands to produce isomorphic movements of a small round cursor on the computer screen. Contacting stimuli with the cursor sometimes resulted in the delivery of different amounts of 45-mg (capuchins) or 94-mg (rhesus) banana-flavored chow pellets (Bio-Serv, Frenchtown, NJ) via a pellet dispenser interfaced to the computer through a digitial I/O board (PDISO8A; Keithley Instruments, Cleveland, OH). Different size pellets were used with each species to account for their different daily caloric needs. The task program was written in source code using Visual Basic 6.0. All monkeys had previously participated in multiple psychological experiments involving this computerized test system (e.g., Beran and Smith, 2011 (link); Beran et al., 2008a (link), 2008b , 2009 (link); Klein et al., 2011 ).

The monkeys were tested using the LRC’s Computerized Test System comprising a personal computer, digital joystick, color monitor, and pellet dispenser (Evans, Beran, Chan, Klein, & Menzel, 2008 ; Richardson, Washburn, Hopkins, Savage-Rumbaugh, & Rumbaugh, 1990 ). Monkeys manipulated the joystick to produce isomorphic movements of a computer-graphic cursor on the screen. Contacting appropriate computer-generated stimuli with the cursor brought them a 45-mg (capuchins) or 94-mg (macaques) banana-flavored chow pellet (Bio-Serv, Frenchtown, NJ) using a pellet dispenser interfaced to the computer through a digital I/O board (PDISO8A; Keithley Instruments, Cleveland, OH). All monkeys had previously participated in multiple psychological experiments involving this computerized test system.