When and for whom do frequencies facilitate performance? On the role of numerical literacy

The thesis that the mind is better prepared to process frequencies—as compared to other numerical formats—continues to be debated. A recent aspect of this issue is the role of numeracy (numerical literacy; one's ability to understand and work with numerical information) and specifically the argument that individual differences in numeracy interact with numerical formats. This interaction, either that frequencies improve performance only for those of low numeracy or that frequencies work only for those of high numeracy, would suggest that better performance using frequencies could be due to (nonevolutionary) numeracy effects. The three present studies revisited prior work with cumulative probability, Bayesian reasoning, and scenario risk assessments to study the effects of numeracy on frequency facilitation. Results from these experiments consistently failed to replicate previous findings of interactions; however, a more consistent finding emerged of a straightforward frequency effect. The lack of interactions and observations of frequency main effects lend support to the evolutionary explanation of the frequency effect. In addition, some possible statistical processes are proposed to explain the observation of interactions in past studies.     

Colour specificity in episodic and in perceptual object recognition with enhanced colour impact

In three experiments we investigated the perceptual specificity of explicit (old-new object recognition) and implicit memory (word-picture matching) for colour. In order to enhance the impact of colour on processing, we increased the number of colours per object and we impaired shape information. We presented multicoloured pictures (Experiment 1), blurred and partially occluded pictures (Experiment 2) and coloured line drawings in visual noise (Experiment 3). Experiments 1 and 2 had an intentional study phase; the study phase of Experiment 3 was an incidental colour or category naming task. Changing colour from study to test always had negative effects on episodic recognition although colour was irrelevant. In contrast, in the matching task old pictures were generally matched faster than new ones independent of their colour congruence. In Experiment 3, an additional small advantage of congruent colours and of semantic processing occurred. We conclude that two different memory representations contribute to these tasks. Changes of an achromatic, more abstract representation, that is used in normal object recognition, and a representation of the specific exemplar that includes colour. This latter token is used in episodic recognition as well as in unusual perceptual tasks (Experiment 3).     

Risk aversion in information seeking

The information gain model argues that participants select alternatives with a larger expected value of information gain. The present study investigated risk aversion in information seeking to examine whether the expected value always determines information-seeking behaviour. For this investigation, we used a scale method selection task in which participants were required to select one of two scales for weighing coins in order to find an underweight coin. Two experiments showed that participants more frequently selected the alternative that provided information gain without risk, although its expected information gain was smaller. This finding indicates the presence of risk aversion in information seeking, suggesting that information-seeking behaviour is affected by risk associated with obtaining information gain.     

Conditioned ethanol aversion in rats induced by voluntary wheel running,forced swimming,and electric shock: An implication for aversion therapy of alcoholism

This study was planned to demonstrate rats’ acquisition of aversion to ethanol solution consumed before voluntary running, forced swimming, or electric shock delivery. Wistar rats under water deprivation were allotted to four groups of eight rats each, and all rats were allowed to drink 5% ethanol solution for 15 min. Immediately after the ethanol drinking, rats of Group Run were put into the individual running wheels for 15 min, those of Group Swim were put into the individual swimming pools for 15 min, those of Group Shock received electric shocks for 15 min (15 0.45-mA shocks of 0.7s with the intershock interval of 1 min) in the individual small chambers, and those of Group Control were directly returned back to the home cages. This procedure was repeated for six days, followed by a two-day choice test of ethanol aversion where a bottle containing 5% ethanol solution and a bottle of tap water were simultaneously presented for 15 min. In the test, Groups Run, Swim, and Shock drank ethanol solution significantly less than tap water, while Group Control drank both fluids equally. The effects of running, swimming, and shock were equivalent. The successful demonstration of acquired ethanol aversion induced by exercise (running and swimming) or shock in rats suggests an avenue for clinical application of exercise and shock treatments for human alcoholics, though there are many issues to be resolved before the practical use.     

Scientific information and uncertainty: Challenges for the use of science in policymaking

Science can reinforce the healthy aspects of the politics of the policy process, to identify and further the public interest by discrediting policy options serving only special interests and helping to select among “science-confident” and “hedging” options. To do so, scientists must learn how to manage and communicate the degree of uncertainty in scientific understanding and prediction, lest uncertainty be manipulated to discredit science or to justify inaction. For natural resource and environmental policy, the institutional interests of government agencies, as well as private interests, pose challenges of suppression, over-simplification, or distortion of scientific information. Scientists can combat these maneuvers, but must also look inward to ensure that their own special interests do not undermine the usefulness of science.     

Clutching at Certainty: Thoughts on the Coercive Grip of Cult-Like Groups

This response to Richard Raubolt's article, Attack on the Self, attempts to understand the intense and enduring connection that often develops between charismatic leaders of cult-like groups and their followers in terms of their mutual need to regulate uncertainty. After describing the intersubjective regulation of uncertainty, a concept influenced by self psychology and intersubjectivity systems theory, a number of uncertainty regulating modes that emerged in the training program are examined including: 1) the denial of difference, 2) the denial of sameness, 3) alter ego relating, 4) the inflamation of passion, and 5) faith-keeping fantasies.     

Possible olfaction-based mechanisms in human kin recognition and inbreeding avoidance

Three studies explored kin recognition through olfaction. In Study I, adults (N=22) were tested for ability to identify the odors of themselves; their mother; their father; a sister; a brother; a familiar, unrelated individual; and a stranger. Acquaintances were identified as accurately as biological kin, implicating an association mechanism. However, biological kin were often confused, implicating phenotypic matching. Same-sex kin were confused more than opposite-sex kin, but mainly when same-sex kin had odors of similar intensity. Study II implicated phenotypic matching. Mothers (N=18) could identify their biological children but not their stepchildren. The preadolescent children (N=37) identified their full siblings but not half-siblings or stepsiblings. Thus, olfactory cues may help mediate favoritism of blood relatives. In Study III, mutual olfactory aversion occurred only in the father-daughter and brother-sister nuclear family relationships. Recognition occurred between opposite-sex siblings but not same-sex siblings. Thus, olfaction may help mediate the development of incest avoidance during childhood (the Westermarck effect).     

Facilitation of Sodium Aversion Learning in Sodium-Deprived Rats

Two experiments with rats explored the effects of sodium deprivation induced by furosemide injections upon acquisition of taste aversion to sodium chloride (NaCl). In Experiment 1, rats under either sodium deprivation or a balanced nutrition condition were given access to a limited amount of NaCl solution prior to poisoning. When all rats were tested under sodium repletion, the previously sodium-deprived rats consumed less NaCl than did the nondeprived rats. This finding was replicated in Experiment 2A in which ingestion of a compound solution of NaCl and hydrochloric acid (HCl) was followed by poisoning. Consumption of HCl, however, showed the opposite pattern: the sodium-deprived rats drank more HCl than did the nondeprived rats, a result that was replicated in Experiment 2B. These results suggest that sodium deprivation strengthens the salience of NaCl, thereby facilitating acquisition of aversion to this taste and strongly overshadowing that to a simultaneously presented taste.     

Drug discrimination using a conditioned taste-aversion paradigm in rhesus monkeys.

The development of drug discrimination was assessed in rhesus monkeys using the conditioned taste-aversion paradigm. Monkeys were initially trained to respond under a fixed-ratio 30-response schedule of food-pellet delivery to assess the rate-decreasing effects of alprazolam (0.03 to 3 mg/kg, i.m., 60 min presession). Alprazolam decreased responding at doses greater than 0.1 mg/kg. Discriminative stimulus effects of alprazolam were then assessed by giving 0.03 mg/kg before sessions in which 1.8 mEq/kg lithium chloride was given immediately after the session (alprazolam/lithium session). On intervening days, saline was given before and after the session (saline/saline session). Rates of responding decreased over successive alprazolam/lithium sessions and also during the saline/saline session that immediately followed an alprazolam/lithium session. During subsequent saline/saline sessions, rates of responding returned to levels near baseline rates within two to four sessions. The discriminative stimulus effects of alprazolam were then assessed by giving 0.1 mg/kg before sessions in which 1 mg/kg d-amphetamine was given immediately after the session (alprazolam/d-amphetamine session). Rates of responding decreased during subsequent alprazolam/d-amphetamine sessions in drug-experienced monkeys, but did not decrease during intervening saline/saline sessions. These findings demonstrate that drug stimuli associated with postsession drug injections can rapidly develop control over behavior and suggest that similar methods be explored in the assessment of drug discrimination.     

Food choice in rats (Rattus norvegicus): the effect of exposure to a poisoned conspecific

Three experiments were conducted to examine the effects of exposure to a poisoned conspecific on subsequent food aversion in rats. In Experiment 1A, rats that had been aversively conditioned to a cocoa-flavored food were exposed to a poisoned conspecific that had eaten the same food. On the subsequent choice test, the animals increased their aversion to that food. These results were reconfirmed in Experiment 1B, in which a cinnamon-flavored food was used as the stimulus. In Experiment 2, subjects were first exposed to a poisoned conspecific and then conditioned to the food which the conspecific had eaten. On the test, they showed no sign of increased aversion to that food.