The Benefits and Challenges of Conducting Primate Research in Different Settings.

Internationally, primate research takes place in laboratories, zoos, sanctuaries, and the wild. All of these settings present unique advantages and challenges in terms of methodology, translatability, animal welfare, and ethics. In this novel commentary, we explore the scientific and ethical benefits and drawbacks of conducting non-invasive psychological research with primates in each setting. We also suggest ways to overcome some of the barriers. We argue that while there may be greater experimental control in laboratory-based research, settings that more closely mirror primates' natural habitats are generally better suited to meet their specialized needs. More naturalistic research settings, including field studies, may also circumvent some ethical concerns associated with research in captivity, and yield more ecologically valid data.

Psychological Distress in Chimpanzees Rescued From Laboratories.

The United States is one of the last countries allowing invasive research on chimpanzees. Biomedical research on chimpanzees commonly involves maternal deprivation, social isolation, intensive confinement, and repetitive invasive procedures. These physically harmful and psychologically traumatic experiences cause many chimpanzees to develop symptoms of psychopathology that persist even after relocation from laboratories to sanctuaries. Through semistructured interviews with chimpanzee caregivers, direct behavioral observations, and consultation of laboratory records, we were interested in qualitatively analyzing symptoms of psychological distress in a sample of 253 chimpanzees rescued from biomedical research now residing at an accredited chimpanzee sanctuary. We present the results of this analysis and include an illustrative case study of one rescued chimpanzee who engages in self-injurious behaviors and meets modified Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for posttraumatic stress disorder. We discuss our results in light of recent policy changes regarding the use of chimpanzees in biomedical research in the United States and their implications for those involved in the rescue and rehabilitation of chimpanzees from biomedical research.

Negative hysteresis in the behavioral dynamics of the affordance "graspable".

One commonly perceives whether a visible object will afford grasping with one hand or with both hands. In experiments in which differently sized objects of a fixed type are presented, the transition from using one of these manual modes to the other depends on the ratio of object size to hand span and on the presentation sequence, with size increasing versus decreasing. Conventional positive hysteresis (i.e., a larger transition ratio for the increasing sequence) can be accommodated by the order parameter dynamics that typify self-organizing systems (Lopresti-Goodman, Turvey, and Frank, Attention, Perception, & Psychophysics 73:1948-1965, 2011). Here we identified and addressed conditions of unconventional negative hysteresis (i.e., a larger transition ratio for the decreasing sequence). They suggest a second control parameter in the self-organization of affordance perception, one that is seemingly regulated by inhibitory dynamics occurring in the agent-task-environment system. Our experimental results and modeling extend the investigation of affordance perception within dynamical systems theory.

Stereotypical behaviors in chimpanzees rescued from the african bushmeat and pet trade.

Many orphaned chimpanzees whose mothers are illegally killed for their meat (bushmeat) in Africa are sold as pets or kept caged at hotels and businesses to attract tourists. As a result of being separated from their mothers and other chimpanzees at an early age, and spending years in impoverished captive conditions, some of these individuals engage in abnormal behaviors, including stereotypically scratching at their flesh and repetitively rocking back and forth. This paper presents case studies of Poco and Safari, two chimpanzees who were rescued by sanctuaries after living alone on display for humans at businesses for the first 7 to 8 years of their lives. Decades after their rescue, they still engage in stereotypical behaviors as a result of the psychological and physical trauma they endured early on. This paper combines data from in depth interviews with caregivers and direct observations of abnormal behaviors to assess psychological distress in captive-living chimpanzees. Our results highlight some lesser known harms of the bushmeat trade and the detrimental life-long consequences that keeping chimpanzees as "pets" can have on their mental health.

Behavioral dynamics of the affordance "graspable".

On a daily basis, one perceives whether an object affords grasping with one hand or with both hands. In experiments in which differently sized objects of a fixed type have been presented, the transition from using one manual mode to the other has depended on both the ratio of object size to hand span and the presentation sequence-that is, size increasing versus decreasing. The transitions and their observed hysteresis (i.e., a transition ratio larger for the increasing sequence) can be accommodated by the order parameter dynamics typifying self-organizing systems. Here, we show that hysteresis magnitude depends on (a) the interaction between the attractors (one hand vs. two hands) and (b) the strength of the two-hands attractor. Through modeling and experimental results, we extend the investigation of affordance perception within dynamical-systems theory.

Order parameter dynamics of body-scaled hysteresis and mode transitions in grasping behavior.

Several experimental studies have shown that human grasping behavior exhibits a transition from one-handed to two-handed grasping when to-be-grasped objects become larger and larger. The transition point depends on the relative size of objects measured in terms of human body-scales. Most strikingly, the transitions between the two different behavioral 'modes' of grasping exhibit hysteresis. That is, one-to-two hand transitions and two-to-one hand transitions occur at different relative object sizes when objects are scaled up or down in size. In our study we approach body-scaled hysteresis and mode transitions in grasping by exploiting the notion that human behavior in general results from self-organization and satisfies appropriately-defined order parameter equations. To this end, grasping transitions and grasping hysteresis are discussed from a theoretical perspective in analogy to cognitive processes defined by Haken's neural network model for pattern recognition. In doing so, issues such as the exclusivity of grasping modes, biomechanical constraints, mode-mode interactions, single subject behavior and population behavior are explored.

Task constraints on affordance boundaries.

The actualization of a simple affordance task-grasping and moving wooden planks of different sizes using either one or two hands-was assessed in the context of task-relevant (plank sequence, plank presentation speed) and task-irrelevant (cognitive load) manipulations. In Experiment 1, fast (3 s/plank) and self-paced ( approximately 5 s/plank) presentation speeds revealed hysteresis; the transition point for ascending series was greater than the transition point for descending series. Hysteresis was eliminated in the slowest presentation speed (10 s/plank). In Experiment 2, hysteresis was exaggerated by a cognitive load (counting backward by seven) for both fast and slow presentation speeds. These results suggest that behavioral responses to the attractor dynamics of perceived affordances are processes that require minimal cognitive resources.

Period basin of entrainment for unintentional visual coordination.

Researchers have demonstrated that a person's rhythmic movements can become unintentionally entrained to another person's rhythmic movements or an environmental event. There are indications, however, that in both cases the likelihood of entrainment depends on the difference between the uncoupled periods of the two rhythms. The authors examined the range of period differences over which unintentional visual coordination might occur in 16 participants (Experiment 1) and 15 participants (Experiment 2). Cross-spectral coherence analysis and the distribution of continuous relative phase revealed that visual entrainment decreased as the difference between participants' preferred period and the experimenter-determined period of the environmental stimulus increased. The present findings extend the dynamical systems perspective on person-environment coupling and highlight the significance of period difference to the emergence of unintentional coordination.