While force-feedback devices have been developed in areas such as virtual reality, there have been very few comparative cognitive studies in nonhuman animals using these devices. In addition, although cross-modal perception between vision and touch has been actively studied in nonhuman primates for several decades, there have been no studies of their active haptic perception. In this study, we attempted to train force discrimination in chimpanzees using a force-feedback device modified from a trackball. Chimpanzees were given different levels of force feedback (8.0 vs. 0.5 N) when moving the on-screen cursor to the target area by manipulating the trackball and were required to select one of two choice stimuli based on the force cue. The experiment was conducted using a trial-block procedure in which the same force stimulus was presented for a fixed number of trials, and the force stimulus was changed between blocks. The block size was progressively reduced from ten trials. Four chimpanzees were trained, but none reached the learning criterion (80% or more correct responses under the condition that the force stimuli were presented randomly). However, a detailed analysis of the chimpanzees’ performance before and after the trial-block switching revealed that their choice behavior could not be explained by a simple win–stay/lose–shift strategy, suggesting that the switching of the force stimuli affected the chimpanzees’ choice behavior. It was also found that the chimpanzees performed better when switching from small to large force stimuli than when switching from large to small force stimuli. Although none of the chimpanzees in this study acquired force discrimination, future studies using such force-feedback devices will provide new insights for understanding haptic cognition in nonhuman primates from a comparative cognitive perspective.

虽然力反馈设备已在虚拟现实等领域得到开发，但对使用这些设备的非人类动物进行的比较认知研究却很少。此外，尽管几十年来人们一直在非人类灵长类动物中积极研究视觉和触觉之间的跨模式感知，但尚未对其主动触觉感知进行研究。在这项研究中，我们尝试使用由轨迹球改造的力反馈装置来训练黑猩猩的力辨别能力。当通过操纵轨迹球将屏幕上的光标移动到目标区域时，黑猩猩会获得不同级别的力反馈（8.0 与 0.5 N），并被要求根据力提示从两种选择刺激中选择一种。该实验使用试验块程序进行，其中针对固定次数的试验提供相同的力刺激，并且在块之间改变力刺激。从十次试验开始，块大小逐渐减小。训练了四只黑猩猩，但没有一只达到学习标准（在随机呈现力刺激的情况下，正确反应为 80% 或以上）。然而，对黑猩猩在试验块切换前后表现的详细分析表明，它们的选择行为不能用简单的赢-留/输-转移策略来解释，这表明力刺激的切换影响了黑猩猩’的选择行为。研究还发现，黑猩猩在从小力刺激切换到大力刺激时比从大力刺激切换到小力刺激时表现更好。尽管这项研究中的黑猩猩都没有获得力辨别能力，但未来使用这种力反馈设备的研究将为从比较认知的角度理解非人类灵长类动物的触觉认知提供新的见解。