Host personality predicts cuckoo egg rejection in Daurian redstarts Phoenicurus auroreus

In species that are subject to brood parasitism, individuals often vary in their responses to parasitic eggs, with some rejecting the eggs while others do not. While some factors, such as host age (breeding experience), the degree of egg matching and the level of perceived risk of brood parasitism have been shown to influence host decisions, much of the variation remains unexplained. The host personality hypothesis suggests that personality traits of the host influence its response to parasitic eggs, but few studies have tested this. We investigated the relationship between two personality traits (exploration and neophobia) and a physiological trait (breathing rate) of the host, and egg-rejection behaviour in a population of Daurian redstarts Phoenicurus auroreus in northeast China. We first show that exploratory behaviour and the response to a novel object are repeatable for individual females and strongly covary, indicating distinct personality types. We then show that fast-exploring and less neophobic hosts were more likely to reject parasitic eggs than slow-exploring and more neophobic hosts. Variation in breathing rate—a measure of the stress-response—did not affect rejection behaviour. Our results demonstrate that host personality, along the bold-shy continuum, predicts the responses to parasitic eggs in Daurian redstarts, with bold hosts being more likely to reject parasitic eggs.

Personality affects dynamics of an experimental pathogen in little brown bats

Host behaviour can affect host–pathogen dynamics and theory predicts that certain individuals disproportionately infect conspecifics during an epidemic. Consistent individual differences in behaviour, or personality, could influence this variation with the most exploratory or sociable individuals most likely to spread pathogens. We quantified exploration and sociability in little brown bats ( Myotis lucifugus ) and then experimentally manipulated exposure to a proxy pathogen (i.e. ultraviolet (UV) fluorescent powder) to test two related hypotheses: (i) more sociable and more exploratory individuals would be more likely to transmit infections to other individuals, and (ii) more sociable and more exploratory individuals uninfected with an invading pathogen would be more likely to acquire infections. We captured 10 groups of 16 bats at a time and held each group in an outdoor flight tent equipped with roosting-boxes. We used hole-board and Y-maze tests to quantify exploration and sociability of each bat and randomly selected one individual from each group for ‘infection’ with non-toxic, UV fluorescent powder. Each group of 10 bats was released into the flight tent for 24 h, which represented an experimental infection trial. After 24 h, we removed bats from the trial, photographed each individual under UV light and quantified infection intensity from digital photographs. As predicted, the exploratory behaviour of the experimentally infected individual was positively correlated with infection intensity in their group-mates, while more exploratory females had higher pathogen acquisition. Our results highlight the potential influence of host personality and sex on pathogen dynamics in wildlife populations.

Learned parasite avoidance is driven by host personality and resistance to infection in a fish–trematode interaction

Cognitive abilities related to the assessment of risk improve survival. While earlier studies have examined the ability of animals to learn to avoid predators, learned parasite avoidance has received little interest. In a series of behavioural trials with the trematode parasite Diplostomum pseudospathaceum , we asked whether sea trout ( Salmo trutta trutta ) hosts show associative learning in the context of parasitism and if so, whether learning capacity is related to the likelihood of infection mediated through host personality and resistance. We show that animals are capable of learning to avoid visual cues associated with the presence of parasites. However, avoidance behaviour ceased after the likely activation of host resistance following consecutive exposures during learning, suggesting that resistance to infection outweighs avoidance. Further, we found a positive relationship between learning ability and boldness, suggesting a compensation of risky lifestyles through increased investment in cognitive abilities. By contrast, an increased risk of infection due to low resistance was not balanced by learning ability. Instead, these traits were positively related, which may be explained by inherent physiological qualities controlling both traits. Overall, the results demonstrate that parasitism, in addition to other biological interactions such as predation, is an important selective factor in the evolution of animal cognition.

Ritual Abuse, Multiplicity, and Mind-Control

As a result of the psychologically intolerable nature of their early childhood experiences, victims of ritual abuse frequently develop multiple personality disorder (MPD). Therapists who treat these victims often assume that all MPD stems from a system of spontaneously created defenses against overwhelming trauma. As a result, these therapists tend to focus on treating the post-traumatic stress elements of the disorder and on integrating alter personalities. Recent experience with victims of ritual abuse suggests the presence of “cult-created” multiplicity, in which the cult deliberately creates alter personalities to serve its purposes, often outside of the awareness of the victim's host personality. Each cult-created alter is programmed to serve a particular cult function such as maintaining contact with the cult, reporting information to the cult, self-injuring if cult injunctions are broken, and disrupting the therapeutic process that could lead to the individual breaking free of the cult. A majority of ritual abuse victims in psychotherapy may maintain cult contact unbeknownst to either the host personality or the treating therapist.

Initial and Follow-up Psychological Testing on a Group of Patients with Multiple Personality Disorder

The Minnesota Multiphasic Personality Inventory (MMPI) and Wechsler Adult Intelligence Scale (WAIS) were administered to the host personality of 18 patients with multiple personality prior to therapy. The MMPI was readministered a mean of 39 mo. later. The MMPI appears to be a valuable aid in diagnosing multiple personality. Characteristic MMPI protocols include (1) high F and Sc scales, (2) technically invalid profiles, (3) numerous critical items, (4) critical items indicating dissociation, (5) a poly-symptomatic picture, (6) wide discrepancy between obvious and subtle scores, (7) lack of blatant psychosis, (8) and infrequently elevated Hs scales. Individuals with borderline to superior IQs may have multiple personality.