Rats can perceive time, according to a new study that tasked them with pressing a button every 3.2 seconds to receive a reward.
Beyond getting to watch a sort of rat-themed game show, the experiment was intended to determine if rats base their behavior only on recent rewards, or if they also could rely on more complex representations of their activities.
For this experiment, those activities revolved around pressing a lever. The paper, published in the journal PNAS, tasked rats with pushing a lever twice with the maximum reward being given for an interval of 3.2 seconds, or alternatively continuously pushing the lever for 3.2 seconds.
Across hundreds of trials, the rats explored pushing the lever and observed what came tumbling through a reward port in response to their performance. Achieving the right time resulted in a reward, and if they repeatedly pushed for the right interval or length of time, they’d receive another.
The researchers were able to further explore the rats’ accuracy by giving greater rewards for attempts closest to 3.2 seconds. Incredibly, all of the rats were able to get the gist of it – and with time, their attempts got closer and closer to the goal time.
“When we saw the first results it was disbelief. We were even thinking, are the rats somehow tricking us?” lead author Tadeusz W?adys?aw Kononowicz told New Scientist. “Our results add a whole new richness to the way that rats represent time [in their minds].”
What this meant was that the rats were assessing how their degree of reward matched up to their behavior and adjusted their timing accordingly to try and achieve the maximum prize. The skill is comparable to an internal stopwatch enabling the animals to time activities and reliably repeat the longevity of a behavior.
“Evaluating the richness of representations mapping animals’ experience of time and space is a profound problem in neuroscience,” explain the authors in the paper.
Their methodology was able to evaluate if the rats were keeping time or simply reacting to rewards, and “the results show that rats track their own timing errors, deepening our understanding of error-monitoring abilities in rodents and the richness of their representation of elapsed time.”