Probing the processing of facial expressions in monkeys via time perception and eye tracking

Accurately recognizing facial expressions is essential for effective social interactions.Non-human primates(NHPs)are widely used in the study of the neural mechanisms underpinning facial expression processing,yet it remains unclear how well monkeys can recognize the facial expressions of other species such as humans.In this study,we systematically investigated how monkeys process the facial expressions of conspecifics and humans using eye-tracking technology and sophisticated behavioral tasks,namely the temporal discrimination task(TDT)and face scan task(FST).We found that monkeys showed prolonged subjective time perception in response to Negative facial expressions in monkeys while showing longer reaction time to Negative facial expressions in humans.Monkey faces also reliably induced divergent pupil contraction in response to different expressions,while human faces and scrambled monkey faces did not.Furthermore,viewing patterns in the FST indicated that monkeys only showed bias toward emotional expressions upon observing monkey faces.Finally,masking the eye region marginally decreased the viewing duration for monkey faces but not for human faces.By probing facial expression processing in monkeys,our study demonstrates that monkeys are more sensitive to the facial expressions of conspecifics than those of humans,thus shedding new light on inter-species communication through facial expressions between NHPs and humans.

Neurotransmitters affecting time perception

BACKGROUND： It has been demonstrated that dopamine and acetylcholine are the main neurotransmitters that affect time perception, which is also affected by other neurotransmitters. OBJECTIVE： To summarize how the neurotransmitter affect the time perception, and put forward the perspectives for further study on time perception. RETRIEVE STRATEGY： An online search for related literatures published in English was conducted in Elsevier SDOL （ScienceDirect Online） database from May 1990 to March 2007 using key words of ＂timing neurotransmitter＂. Totally 69 literatures were collected, and they were primarily checked. Inclusive criteria： Reviews and experimental studies; correlative studies of timing neurotransmitter. Exclusive criteria： Repeated studies. LITERATURE EVALUATION： The literatures were mainly sourced from Cognitive Brain Research and Neuroscience, and they were analyzed according to the inclusive criteria. Nineteen of them were involved, and all were experimental studies and reviews. DATA SYNTHESIS： The studies on time perception are developed mainly concentrating on dopamine and acetylcholine. Dopamine D2 receptors mainly affect the speed of internal clock. Dopamine receptors play an important role in both timing excitation and inhibition, which suggests the bi-directional regulation of dopamine. Injection of dopamine agonist can affect the attention to timing information. Injection of BW813U （antagonist of acetylcholine） can induce memory disorder, which indicates the effect of acetylcholine on timing memory, and further study shows that it is the effect of acetylcholine in precentral medial area. In a word, the study on the neurotransmitters affecting time perception is still at the primary stage. CONCLUSION： Dopamine and acetylcholine are the neurotransmitters known to be related to time perception. Dopamine in the basal ganglia is related to internal-clock in the range of seconds and minutes; Acetylcholine in prefrontal cortex is related to the mechanisms of temporal memory and attention. Studies of neurotransmitter provide an approach to acknowledge on the neuromechanism of time perception.

Toward time-based design： Creating an applied time evaluation checklist for urban design research

The perception of a 3D space, in which movement takes place, is subjectively based on experience. The pedestrians＇ perception of subjective duration is one of the related issues that receive tittle attention in urban design Literature. Pedestrians often misperceive the required time to pass a certain distance. A wide range of factors affects one＇s perception of time in urban environments. These factors include individua（ factors （e.g., gender, age, and psychoLogicaL state）, social and cu（tural contexts, purpose and motivation for being in the space, and knowledge of the given area. This study aims to create an applied checklist that can be used by urban designers in analyzing the effects of individual experience on subjective duration. This checklist wilt enable urban designers to perform a phenomenotogicat assessment of time perception and compare this perception in different urban spaces, thereby improving pedestrians＇ experiences of time through a purposeful design. A combination of exploratory and descriptive anaLyticaL research is used as methodology due to the complexity of time perception.