Metacognitive monkeys or associative animals? Simple reinforcement learning explains uncertainty in nonhuman animals

Monkeys will selectively and adaptively learn to avoid the most difficult trials of a perceptual discrimination learning task. Couchman, Coutinho, Beran, and Smith (2010) have recently demonstrated that this pattern of responding does not depend on animals receiving trial-by-trial feedback for their responses; it also obtains if experience of the most difficult trials occurs only under conditions of deferred feedback. Couchman et al. argued that this ruled out accounts based on low-level processes of associative learning and instead required explanation in terms of metacognitive processes of decision monitoring. Contrary to this argument, a simple associative model of reinforcement learning is shown to account for the key findings of Couchman et al.'s empirical study, along with several other findings that have previously been claimed to challenge associative models.     

What lies behind postnatal depression: is it only a mood disorder?

Postnatal depression (PND) is a common condition that has been extensively researched specifically because of its negative impact on the mother-infant relationship. Psychiatric research has looked at comorbidity of major depressive disorder and found it to be strongly associated with Axis II disorders. This study's principal aim was to investigate whether there is a greater incidence of personality disorder (PD) among a PND population than among a non-PND population at 3 months postpartum. A secondary aim was to define the different types of PD. Depression was assessed with the Montgomery and Asberg Depression Rating Scale (MADRS), and PD was assessed with the Structured Interview for DSM-IV Personality Disorders (SIDP-IV) in 109 women with their 12-week-old infants. Twice as many depressed mothers had PD. The PND group presented a greater number of severe clinical symptoms than the nondepressed group (p < .002). Further research is necessary to reexamine the heterogeneity of PND and reassess its impact on infant development.     

Long-term effects of footshock and social defeat on anxiety-like behaviours in rats: Relationships to pre-stressor plasma corticosterone concentration

We compared the consequences of two stressors, 'unnatural' inescapable footshocks (IFSs) and 'natural' social defeat (SD), on behaviours typically sensitive to stress [sucrose preference, open field (OF), elevated plus maze (EPM) and acoustic startle responses (ASRs)] and the association with pre-stressor plasma corticosterone concentration. After initial blood sampling, rats (n?=?20 per group) were exposed to either 10 IFSs (1?mA intensity, 5?s duration each) or to 1?h SD (defeat by an aggressive resident male rat and further exposure but separated in a small cage) or to control procedures (handling). Rats were tested once for ASR (day 19), while the other behavioural tests were applied once weekly for 3 weeks. Both stress groups showed short-lasting lowered sucrose preference, and in the EPM they showed shorter total distance moved, shorter distance moved on open arms and less time on open arms compared to controls. In the OF test, IFS rats showed shorter total distance moved up to 2 weeks after stress. The SD group showed shorter total distance moved in the OF, which was only significant 2 weeks after stress. Low pre-stressor plasma corticosterone concentration was only associated with defecation (IFS rats) and latency to enter open arms in the EPM (all low corticosterone subgroups, n?=?10 per subgroup). SD rats with high initial plasma corticosterone concentration showed enhanced ASR compared to the other subgroups with high initial plasma corticosterone concentration (n?=?9 per subgroup). The results indicate that footshock and SD, while generally leading to an increase in anxiety behaviours, represent qualitatively different stressors.     

Research participation improves student's exam performance

Although there have been several attempts to explore for beneficial effects of research participation in social sciences, most of them have mainly explored satisfaction and students learning perceptions (e.g., Bowman & Waite, 2003). Very few works have studied learning by measuring exam performance. Moreover, participation has been usually conceptualized as a mixture of active and passive participation, including in the same measure different practices such as filling up questionnaires, running experiments or reading and answering questions about a journal article or a scientific conference. The present work tries to determine if there is an advantage due to research participation comparing exam performance, satisfaction and perceived learning of the matter Research Methods in Psychology, in three different groups (non-participating, passive and active participating). As we can see in the results, the mere participation benefits exam performance. Results are discussed in terms of the use of research participation as a new powerful active method in education.     

Domestic dogs (Canis familiaris) flexibly adjust their human-directed behavior to the actions of their human partners in a problem situation

Domestic dogs (Canis familiaris) have been shown to actively initiate triadic communicative interactions by looking at a human partner or by alternating their gaze between the human and an object when being faced with an out-of-reach reward or an unsolvable problem. It has hardly been investigated, however, whether dogs flexibly adjust their human-directed behavior to the actions of their partners, which indicate their willingness and abilities to help them when they are faced with a problem. Here, in two experiments, we confronted dogs—after initially allowing them to learn how to manipulate an apparatus—with two problem situations: with an empty apparatus and a blocked apparatus. In Experiment 1, we showed that dogs looked back at their owners more when the owners had previously encouraged them, independently from the problem they faced. In Experiment 2, we provided dogs with two experimenters and allowed them to learn through an initial phase that each of the experimenters could solve one of the two problems: the Filler re-baited the empty apparatus and the Helper unblocked the blocked apparatus. We found that dogs could learn to recognize the ability of the Filler and spent time close to her when the apparatus was empty. Independently from the problem, however, they always approached the Helper first. The results of the present study indicate that dogs may have a limited understanding of physical problems and how they can be solved by a human partner. Nevertheless, dogs are able to adjust their behavior to situation-specific characteristics of their human partner’s behavior.     

Hypertonic saline mimics the effects of vasopressin on inhibitory avoidance in the rat

Rats tested in a step-through inhibitory avoidance task were administered hypertonic saline (2 ml of 0.25. 0.5, and 1.0 M intraperitoneally) or arginine vasopressin (1.0, 2.0, and 4.0 micrograms) injected subcutaneously (sc) after the training trial where the rats received a mild footshock (0.2 mA, 3 s). Both hypertonic saline and vasopressin produced significant increases in latency to reenter 24 h later. These treatments failed to increase reentry latencies in animals that received the same procedure but no shock. The facilitation of inhibitory avoidance produced by hypertonic saline was reversed by sc administration of 25 micrograms of the vasopressor (V-1) vasopressin antagonist, dPtyr(Me)AVP. The results suggest that the endogenous release of vasopressin can be behaviorally significant in situations of acute homeostatic challenge.