Caffeine affects the vigilance decrement of Trite planiceps jumping spiders (Salticidae)

In jumping spiders (Salticidae), the vigilance decrement, or decrease in response to a repeated visual stimulus over time, directly parallels that found in humans. Explanations for the vigilance decrement in the human literature are heavily mentalistic and central nervous system (CNS) based, whereas response decrements in invertebrates are typically thought of as habituation at the sensory periphery. Here we explored whether the salticid vigilance decrement could be CNS modulated by using caffeine, which is a well-known CNS stimulant for both vertebrates and invertebrates. We used paired tests in which Trite planiceps Simon spiders were randomly given a drop of either caffeinated water or distilled water and were then shown dot stimuli presented on monitors. We measured both general "walking," or activity, as a control for physical fatigue, and optomotor responses to the stimuli. We found that the vigilance decrement was significantly shallower (i.e., spiders were more responsive for longer) when spiders were administered caffeine compared with water; furthermore, these spiders were also generally more active throughout the testing period and thus were not physically impaired. Our results suggest that, in at least some invertebrates, CNS modulation of the vigilance decrement is likely. (PsycINFO Database Record (c) 2019 APA, all rights reserved).