Adaptive Choice Biases in Mice and Humans

Abstract

The contribution of non-sensory information processing to perceptual decision making is not fully understood. Choice biases have been described for mice and humans and are highly prevalent even if they decrease rewarding outcomes. Choice biases are usually reduced by discriminability because stimulus strength directly enables the adjustments in the decision strategies used by decision-makers. However, choice biases could also derive from functional asymmetries in sensory processing, decision making, or both. Here, we tested how particular experimental contingencies influenced the production of choice biases in mice and humans. Our main goal was to establish the tasks and methods to jointly characterize psychometric performance and innate side-choice behavior in mice and humans. We implemented forced and un-forced visual tasks and found that both species displayed stable levels of side-choice biases, forming continuous distributions from low to high levels of choice stereotypy. Interestingly, stimulus discriminability reduced the side-choice biases in forced-choice, but not in free-choice tasks. Choice biases were stable in appearance and intensity across experimental days and could be employed to identify mice and human participants. Additionally, side- and alternating choices could be reinforced for both mice and humans, implying that choice biases were adaptable to non-visual manipulations. Our results highlight the fact that internal and external elements can influence the production of choice biases. Adaptations of our tasks could become a helpful diagnostic tool to detect aberrant levels of choice variability.

Isomorphic decisional biases across perceptual tasks

“…At the extreme, high levels of choice stereotypy characterize some human psychopathologies and mental disorders [ 10 ]. Similar manifestations of sub-optimal choice behavior have also been documented for rats [ 11 ], mice [ 6 , 12 , 13 ], and pigeons [ 14 ].…”

“…We thus hypothesized that if human participants stably exhibit side-choice biases, they should co-vary with other behavioral metrics when the same individuals solved unrelated tasks. Employing forced and unforced tasks [ 13 ], we confirmed that participants exhibited different but consistent proportions of side-choice biases ( i . e ., decisional biases) across experimental days.…”

“…To separately quantify visually guided choices and side-choice biases, we implemented a two-alternative forced-choice (2AFC) match-to-sample visual task (1 st forced visual choice) coupled with a second unforced-choice phase (2 nd free side-choice), as described in detail previously [ 13 ]. Briefly, participants sat upright in front of a computer monitor while we recorded their responses using a conventional joystick (Thrustmaster 2960623 USB Joystick; 1000 Hz) connected to a standard computer (Intel (R) Xeon (R) @ 3.40 GHz; 64 Bit Operating system; Graphics card: NVIDIA Quadro K600, 8 G.B.…”

“…Similarly, decisional ( i . e ., non-perceptual) side-choice biases can be studied through unforced choice (2AUC) tasks with equally rewarded alternatives [ 13 , 19 , 20 ]. Thus, in the 2AUC approach, the discriminative stimulus does not predict reward.…”

“…Interestingly, using the latter task, we have found that decisional biases were independent of stimulus discriminability and the predictive value of sensory stimuli. We also found that side-choice behavior varied widely across participants but was stable for each individual across experimental days, suggesting the existence of diverse task-solving strategies [ 13 ].…”