Abstract:
Scientific investigation of the sensory world and behavior of the tuatara is limited. This study
incorporates both ecological and psychological perspectives to test learning and visual
perception using a novel operant technique and flicker-fusion rates to measure visual
discrimination in tuatara. We posed four main questions: (1) can a reliable method examine
learning and visual perception in tuatara?, (2) what is the critical flicker-fusion (CFF) rates
for tuatara and how does it relate to motion detection ability?, (3) can stimulus control be
transferred to a Y-maze from an open field arena?, and (4) what are the implications for
behavioral ecology, conservation, and species welfare? Tuatara (Sphenodon punctatus) were
trained using an operant conditioning procedure with food reinforcement to respond to
discriminative stimuli (S+) of various flicker-fusion rates, and ignore a non-discriminative
stimulus (S-). Tuatara discriminated CFF rates between 2.65-45.61 Hz, but not at 65.09 Hz.
The upper threshold between 45.61-65.09 Hz is comparable to other mammalian, avian, and
herpetological species. Tuatara demonstrated a learning capacity for acquisition of an
operant task as well as cognitive development for learning and memory strategies. Visual
discrimination is important to tuatara and may facilitate behavioral responses to many
context-dependent ecological processes (i.e., predator/prey/kin recognition, mate selection,
environmental discrimination, optimal foraging strategies, and communication). By
understanding the importance of visual stimuli, the study provides a better perspective of the
tuatara natural sensory world. Additionally, a reliable method was established that can be
used for more comprehensive psychophysical experiments to further access visual perception
and learning in all reptiles, with the potential to examine other sensory mechanisms such as
audition, chemoreception, and tactility.
