Making inferences about the location of hidden food: social dog, causal ape

Domestic dogs (Canis familiaris) and great apes from the genus Pan were tested on a series of object choice tasks. In each task, the location of hidden food was indicated for subjects by some kind of communicative, behavioral, or physical cue. On the basis of differences in the ecologies of these 2 genera, as well as on previous research, the authors hypothesized that dogs should be especially skillful in using human communicative cues such as the pointing gesture, whereas apes should be especially skillful in using physical, causal cues such as food in a cup making noise when it is shaken. The overall pattern of performance by the 2 genera strongly supported this social-dog, causal-ape hypothesis. This result is discussed in terms of apes' adaptations for complex, extractive foraging and dogs' adaptations, during the domestication process, for cooperative communication with humans.     

Preexisting knowledge versus on-line learning: what do young infants really know about spatial location?

Contemporary knowledge of infant cognition relies heavily on violation-of-expectation experiments. However, there are two ways to conceptualize what occurs in such studies. Babies may react to anomalous test events because of preexisting world knowledge. Alternatively, they may react because they have learned about events during the familiarization period. One way to distinguish these possibilities is to contrast familiarization with everyday versus anomalous events. In the studies we report here, we used this method to probe the nature of 5-month-olds' expectations about the locations of objects hidden in sand and later revealed. In Experiment 1, infants who initially saw everyday events did react to anomalous ones, as found previously, whereas infants who initially saw anomalous events did not react to everyday events. In Experiment 2, two alternative explanations of this pattern were ruled out. We conclude that by the age of 5 months, infants have expectations regarding the location of objects in continuous space.     

Adult age differences in the implicit and explicit components of top-down attentional guidance during visual search

Two experiments investigated adult age differences in the explicit (knowledge-based) and implicit (repetition priming) components of top-down attentional guidance during discrimination of a target singleton. Experiment 1 demonstrated an additional contribution of explicit top-down attention, relative to the implicit effect of repetition priming, which was similar in magnitude for younger and older adults. Experiment 2 examined repetition priming of target activation and distractor inhibition independently. The additional contribution of explicit top-down attention, relative to the repetition priming of distractor inhibition, was greater for older adults than for younger adults. The results suggest that some forms of top-down attentional control are preserved as a function of adult age and may operate in a compensatory manner.     

Do warnings of response verification moderate the relationship between personality and cognitive ability?

This article presents the results of 2 studies that examine the effect of presenting a warning of response verification by others on the relationship between measures of personality and cognitive ability. In both a field study and a laboratory study, stronger correlations were generally found between measures of personality and cognitive ability when a warning of verification was present. The results from the studies also showed that the warning of verification was associated with slower item response latencies for certain personality scales, suggesting that exposure to the warning increased the complexity of the response decision. Results are discussed in terms of the effects of altering test instructions on the construct validity of personality measures used in applied settings.     

Hope against the cold: individual differences in trait hope and acute pain tolerance on the cold pressor task

Hope theory (see Snyder, 1994) is presented as a useful framework for understanding reactions to pain. In Study 1, persons scoring higher on the trait Hope Scale (Snyder, Harris et al., 1991) kept their hands in the freezing water (of a cold pressor task) for significantly longer. In Study 2, the higher-hope males, and not females, as measured by both trait and state hope (Snyder, Sympson et al., 1996), recognized the onset of the pain threshold significantly later. Moreover, in Study 2, results showed that individual differences measures of optimism, self-efficacy, depression, and positive and negative affects did not relate to the pain onset and tolerance variables. The implications of hope as related to the pain process and related research are discussed.     

Development of a portable psychometric testing device for use in the field: an alcohol investigation

Cognitive and psychomotor performance have traditionally been assessed in the laboratory. There is a need for an objective portable assessment tool to assess cognitive and psychomotor performance. This study investigated the viability of a portable psychometric test battery, in a controlled laboratory environment, possibly leading to use in the field. A randomised, double-blind placebo controlled, three-way crossover design was employed. 16 subjects received 50 mg/100 ml and 80 mg/100 ml of alcohol and alcohol placebo. Performance was assessed with a tracking task, and an attention task presented on a small ruggedised handheld computer. The attention task showed no significant training effects; however, an element of the tracking task did. Statistical significance, effect size, and test-retest reliability analyses are presented indicating sensitivity of the portable psychometric test battery to the impairing effects of two separate doses of alcohol. Ability to undertake wide-scale impairment testing in the field with meaningful results in the absence of baseline data collection may have wide reaching implications, particularly in relation to the assessment of drivers impaired by drug use.     

Unconscious affective reactions to masked happy versus angry faces influence consumption behavior and judgments of value

The authors explored three properties of basic, unconsciously triggered affective reactions: They can influence consequential behavior, they work without eliciting conscious feelings, and they interact with motivation. The authors investigated these properties by testing the influence of subliminally presented happy versus angry faces on pouring and consumption of beverage (Study 1), perception of beverage value (Study 2), and reports of conscious feelings (both studies). Consistent with incentive motivation theory, the impact of affective primes on beverage value and consumption was strongest for thirsty participants. Subliminal smiles caused thirsty participants to pour and consume more beverage (Study 1) and increased their willingness to pay and their wanting more beverage (Study 2). Subliminal frowns had the opposite effect. No feeling changes were observed, even in thirsty participants. The results suggest that basic affective reactions can be unconscious and interact with incentive motivation to influence assessment of value and behavior toward valenced objects.     

On the determinants of induction in responding for sucrose when food pellet reinforcement is upcoming

Rats' rates of leverpressing for low-concentration liquid-sucrose reinforcers in the first half of an experimental session increase when food pellet, rather than sucrose, reinforcers will be available in the second half. Experiment 1 determined that this induction effect was the outcome of food pellet reinforcement's increasing response rates, not of continued sucrose reinforcement's decreasing them. Experiments 2 and 3 showed that induction was primarily controlled by the conditions of reinforcement in the current session, not by those in the previous one. Experiment 4 showed little evidence that the induction was the outcome of Pavlovian processes. These results suggest that induction may occur because of processes operating at the level of the entire session. They also provide a link to a seemingly related area of study: contrast effects. Some of the results are consistent with what is known about contrast effects, but there are also several, yet unexplained differences.