Chronic amphetamine exposure during the preweanling period does not affect avoidance learning or novelty-seeking of adult rats

The purpose of the present study was to determine whether exposure to amphetamine during the preweanling period would impact the learning or reward processes of rats tested in adulthood. In three experiments we examined whether amphetamine treatment (0-10 mg/kg per day) on postnatal days 11-17 altered the subsequent performance of adult Sprague-Dawley rats on a step-down passive avoidance, active avoidance, or novelty-seeking task. There was no evidence that postnatal amphetamine exposure affected performance on any of these tasks. These results suggest that the long-term impact of pre- and postnatal psychostimulant exposure differs, because in utero stimulant treatment is known to produce learning deficits and decrease reinforcement efficacy of rats tested in adulthood.     

Effects of the Novel Acetylcholinesterase InhibitorN-Octyl-1,2,3,4-tetrahydro-9-aminoacridine on Locomotor Activity and Avoidance Learning in Mice

The acetylcholinesterase reversible inhibitorN-octyl-1,2,3,4-tetrahydro-9-aminoacridine (THA-C8) is a new synthesized derivative of tacrine (THA) characterized by an alkyl chain in the molecular structure which ameliorates the penetrability of the compound into the central nervous system. THA-C8 (0.1–5 mg/kg) significantly reduced spontaneous locomotor activity in CD1 mice at a dose of 3 mg/kg. Moreover, THA-C8 (0.2–2 mg/kg) significantly improved shuttle-box avoidance acquisition at doses (0.25, 0.3, 1 mg/kg) not affecting locomotion and that are much lower than the doses reported to be effective for THA in animal models. From the data reported it seems that the new compound could be interesting for therapeutic purposes.     

Interactive learning in the paradise fish (Macropodus opercularis): an ethological interpretation of the second-order conditioning paradigm

This study was aimed at the examination of ‘mental construction’ in paradise fish by interactive learning, which is suggested as an alternative hypothesis for backward or second-order conditioning. Avoidance of goldfish was established in paradise fish by presenting a harmless goldfish (a novel stimulus) after an aversive event (mild electric shocks) in the dark compartment of a shuttle tank. It was found that this avoidance depended on context pre-exposure. Experiment 1 was designed to study the effect of mild shocks on shuttling activity in a familiar context. Experiment 2 aimed at establishing fear-conditioning to the goldfish in a higher-order conditioning paradigm. In the course of training, unpaired stimuli were presented in the dark compartment of the shuttle tank in such a manner that the presentation of mild shocks (20 mA) preceded the encounter with a harmless fish (goldfish). Experiment 3 demonstrated the role of context pre-exposure in interactive learning. Results indicate that (1) while 60 mA shocks resulted in avoidance of the dark compartment, the 20 mA mild shocks affected exploratory behaviour; (2) after pre-exposure to the training environment, paradise fish avoided the dark compartment containing goldfish provided that subjects had previously encountered mild, explorative shocks there; (3) this conditioned fear, a ‘mental construction’ of a potential danger, was proved to be transferable to another context and was consequently aimed specifically at the goldfish, a living being, rather than the training context; (4) the pre-exposure to the shuttle tank was an important part of this training procedure, that is, only subjects habituated to the shuttle tank avoided the goldfish. Results are discussed in the framework of the Interactive Learning Hypothesis, which has been developed as an ethological approach to a higher-order conditioning paradigm. Received: 15 January 1999 / Accepted after revision: 18 August 1999     

Distractor effect on the latent inhibition of conditioned flavor aversion in rats

Using a conditioned flavor aversion procedure with rats as subjects, the effect of the addition of a distractor stimulus on the magnitude of the latent inhibition effect was examined. Experiment 1 showed that latent inhibition to vinegar was attenuated by the addition of sucrose during preexposure. On the other hand, sucrose added during conditioning to vinegar did not attenuate latent inhibition. It was also found that the degree of latent inhibition to the vinegar-sucrose compound solution was less when vinegar alone was preexposed (i.e., when sucrose was added only during conditioning) than when the compound solution was preexposed (i.e., when sucrose was added both during preexposure and during conditioning). Experiment 2 gave similar results but with sucrose assigned as the target flavor and vinegar as the distractor. These findings are in full agreement with the generalization decrement account of latent inhibition.     

Disgusting clusters: trypophobia as an overgeneralised disease avoidance response

Individuals with trypophobia have an aversion towards clusters of roughly circular shapes, such as those on a sponge or the bubbles on a cup of coffee. It is unclear why the condition exists, given the harmless nature of typical eliciting stimuli. We suggest that aversion to clusters is an evolutionarily prepared response towards a class of stimuli that resemble cues to the presence of parasites and infectious disease. Trypophobia may be an exaggerated and overgeneralised version of this normally adaptive response. Consistent with this explanation, individuals with trypophobia, as well as comparison individuals, reported aversion towards disease-relevant cluster stimuli, but only the trypophobic group reported aversion towards objectively harmless cluster stimuli that had no relevance to disease. For both groups the level of aversion reported was predicted uniquely by a measure of disgust sensitivity. Scaled emotion ratings and open-ended responses revealed that the aversive response was predominantly based on the disease avoidance emotion, disgust. Many open-ended responses also described skin sensations (e.g. skin itching or skin crawling). These findings support the proposal that individuals with trypophobia primarily perceive cluster stimuli as cues to ectoparasites and skin-transmitted pathogens.     

The nature and consequences of topic avoidance in Chinese and Taiwanese close relationships

Two studies examined topic avoidance in Chinese and Taiwanese opposite‐sex friendships and romantic relationships. Five areas of topic avoidance emerged through analytic induction and cluster analysis: negative appraisal, relational issues, sexual issues, politics, and personal experience. Partner protection, negative relational impact, and self inefficacy emerged as the most common reasons for avoidance. Results revealed that friends, relative to romantic partners, engaged in higher levels of topic avoidance. Taiwanese participants, moreover, avoided discussing politics to a greater extent than did mainland Chinese participants. Lacking closeness was the main reason behind avoidance of political discussion. Topic avoidance was also linked to relationship quality, as relational satisfaction negatively predicted relational issue avoidance and topic avoidance breadth (i.e. the number of topics regularly avoided in the relationship). The authors explain these and other findings based on Chinese cultural codes and historically‐embedded concepts that shape interpersonal interaction.     

The preference for symmetry in flower-naïve and not-so-naïve bumblebees

Truly flower-naïve bumblebees, with no prior rewarded experience for visits on any visual patterns outside the colony, were tested for their choice of bilaterally symmetric over asymmetric patterns in a radial-arm maze. No preference for symmetry was found. Prior training with rewarded black and white disks did, however, lead to a significant preference for symmetry. The preference was not specific to symmetry along the vertical axis: a preference for horizontal symmetry was found as well. The results challenge the notion that a preference for bilateral symmetry is unlearned. The preference for symmetry was the product of non-differential conditioning.     

Analysis of the US-preexposure effect in flavor acceptance conditioning

In three experiments, rats received exposure to a sucrose solution followed by conditioning with a neutral flavor as the conditioned stimulus (CS) and sucrose as the unconditioned stimulus (US). In Experiments 1 and 2, some rats were given both the preexposure and the conditioning phases in a highly familiar context (the homecage), whereas other animals received both phases in a novel and distinctive context. In both cases the magnitude of the conditioning effect was reduced by preexposure to the US. Experiment 3 directly assessed the possible role of contextual cues by changing the context between the exposure phase and the conditioning phase but found no loss of the US-preexposure effect in these conditions. These results lend no support to the blocking-by-context account of the US-preexposure effect; alternative interpretations are considered.     

An Experimental Test of the Effects of Parental Modeling on Panic-Relevant Escape and Avoidance Among Early Adolescents

Escape and avoidance behaviors play a prominent role in the maintenance and possibly development of panic disorder, yet the literature regarding the etiology of these emotion-regulation strategies is relatively underdeveloped. The current study experimentally tests hypotheses that parental modeling of escape during a well-established panic-relevant biological challenge increases panic-relevant escape and avoidance among offspring. Fifty physically and psychologically healthy early adolescents (28 females; M_age = 11.58; 86% Caucasian), stratified by gender, were randomly assigned to observe one of their parents (39 females; M_age = 40.04): either (a) model completing a 3-min voluntary hyperventilation exercise (no escape modeling group) or (b) model premature termination of a similar procedure (escape modeling group). Offspring in the escape modeling group demonstrated a stronger escape response by discontinuing their own challenge sooner than those in the no-escape modeling group (r = .70). No group differences emerged in terms of avoidance responding, as indexed by nearly identical responding in terms of delay time before initiating the challenge, respiration rate, and self-reported willingness to engage in a second proposed challenge. Results suggest that parental behaviors may play an important role in the development of some forms of panic-relevant responding. These preliminary findings may have important implications for future prevention programs targeting parents and at-risk youth.     

Thyme to touch: Infants possess strategies that protect them from dangers posed by plants

Plants have been central to human life as sources of food and raw materials for artifact construction over evolutionary time. But plants also have chemical and physical defenses (such as harmful toxins and thorns) that provide protection from herbivores. The presence of these defenses has shaped the behavioral strategies of non-human animals. Here we report evidence that human infants possess strategies that would serve to protect them from dangers posed by plants. Across two experiments, infants as young as eight months exhibit greater reluctance to manually explore plants compared to other entities. These results expand the growing literature showing that infants are sensitive to certain ancestrally recurrent dangers, and provide a basis for further exploration.