Generating alternatives: A key component in human reasoning?

According to mental models theory, a key aspect of deductive reasoning is the production of alternative models that can falsify provisional conclusions. In the present paper, the possibility is investigated that there are individual differences in the ability to produce alternative models. The results indicate that some people do not proceed beyond the first model when they reason with syllogisms but that others do. Furthermore, the ability to generate alternatives can be independently measured by asking participants to generate different representations of pairs of premises. These findings support the predictions of mental models theory and also indicate the potential importance of alternatives generation as a measure of individual differences in processing style.     

Plumbing semantic depths in Amsterdam

The 13th Amsterdam Colloquium was held at the Institute for Logic, Language and Linguistics at the University of Amsterdam, on 17-19 December 2001.     

Construction of preferences by constraint satisfaction

Participants were given a choice between two multiattribute alternatives (job offers). Preferences for the attributes were measured before, during, and after the choices were made. We found that over the course of decision making, the preferences shifted to cohere with the choice: The attributes of the option that was eventually chosen came to be rated more favorably than they had been rated initially, while the attributes of the rejected option received lower preference ratings than before. These coherence shifts were triggered by a single attribute that decisively favored one option (Experiment 1), and occurred spontaneously in the absence of a decisive attribute (Experiment 2). The coherence shift preceded commitment to choice. These findings favor constraint-satisfaction models of decision making.     

Bias at the racetrack: effects of individual expertise and task importance on predecision reevaluation of alternatives

These studies were designed to test cognitive dissonance theory's assertion that alternatives are not reevaluated before a choice. Participants viewed information about horses in a simulated race and rated each one's chance of winning three times before placing their bet and once after placing it. It was found that ratings of the chosen horse increased within the predecision period as well as after betting. Predecision bolstering occurred even when participants did not expect to bet, and predecision preference increased with task importance and participant expertise. The findings are attributed to maintenance of consistency throughout a cognitive system.     

Estimation and interpretation of 1/f<Superscript>α</Superscript> noise in human cognition

Recent analyses of serial correlations in cognitive tasks have provided preliminary evidence of the presence of a particular form of long-range serial dependence known as 1/fnoise. It has been argued that long-range dependence has been largely ignored in mainstream cognitive psychology even though it accounts for a substantial proportion of variability in behavior (see, e.g., Gilden, 1997, 2001). In this article, we discuss the defining characteristics of long-range dependence and argue that claims about its presence need to be evaluated by testing against the alternative hypothesis of short-range dependence. For the data from three experiments, we accomplish such tests with autoregressive fractionally integrated moving-average time series modeling. We find that long-range serial dependence in these experiments can be explained by any of several mechanisms, including mixtures of a small number of short-range processes.     

Self-cutting: patient characteristics compared with self-poisoners

A large ( n = 14,892) consecutive sample of deliberate self-harm (attempted suicide) patients who presented to a general hospital in the United Kingdom during a 23-year study period was examined (over two consecutive time periods) in order to compare the characteristics of those who used self-cutting ( n = 428) and those who self-poisoned ( n = 11,065). Patients who used different methods on other occasions, or were not assessed by the psychiatric service, were excluded. In the first time period (January 1976-June 1988), the self-cutters were distinguished from the self-poisoners by more often being male, single, not employed, and having a history of previous deliberate self-harm. In the second time period (July 1988-December 1998) the self-cutters were again distinguished by more often being male and having a history of previous deliberate self-harm, but also by being more likely to live alone, misuse alcohol, and have low suicidal intent scores. The finding of an excess of males among the self-cutters is contrary to the impression in the literature that self-cutting presentations to general hospitals more often involve females. It also indicates that the treatment needs of those who deliberately cut themselves are likely to differ from those of self-poisoners.     

Galantamine facilitates acquisition of a trace-conditioned eyeblink response in healthy, young rabbits

Previous work has demonstrated that drugs increasing brain concentrations of acetylcholine can enhance cognition in aging and brain-damaged organisms. The present study assessed whether galantamine (GAL), an allosteric modulator of nicotinic cholinergic receptors and weak acetylcholinesterase inhibitor, could improve acquisition and retention of an eyeblink (EB) classical conditioning task in healthy, young animals. We trained 24 rabbits (n = 8/group) in a 1000-msec trace Pavlovian EB conditioning paradigm in which a tone conditioned stimulus (CS) was presented for 500 msec, followed by a 500-msec trace period in which no stimuli were presented. A 100-msec corneal airpuff was the unconditioned stimulus (US). Acquisition sessions, consisting of 100 trials each, occurred daily for 10 consecutive days, followed by 3 d of extinction training. Animals were treated with one of three doses of GAL (0.0-3.0 mg/kg) prior to each session. Animals that received 3.0 mg/kg GAL showed significantly more EB conditioned responses (CRs) in fewer training trials than animals receiving either 1.5 mg/kg GAL or vehicle injections. GAL had no effect on CR performance during extinction. Pseudoconditioning control experiments, consisting of 200 explicitly unpaired tone-puff presentations indicated that GAL did not increase reactivity to the CS or US. These findings indicate that GAL may improve acquisition of moderately difficult associative learning tasks in healthy young organisms.     

Dissimilar items benefit from phonological similarity in serial recall

In short-term serial recall, similar sounding items are remembered less well than items that do not sound alike. This phonological similarity effect has been observed with lists composed only of similar items, and also with lists that mix together similar and dissimilar items. An additional consistent finding has been what the authors call dissimilar immunity, the finding that ordered recall of dissimilar items is the same whether these items occur in pure dissimilar or mixed lists. The authors present 3 experiments that disconfirm these previous findings by showing that dissimilar items on mixed lists are recalled better than their counterparts on pure lists if order errors are considered separately from intrusion errors (Experiment 1), or if intrusion errors are experimentally controlled (Experiments 2 and 3). The memory benefit for dissimilar items on mixed lists poses a challenge for current models of short-term serial recall.     

The visual control of reaching and grasping: binocular disparity and motion parallax

The primary visual sources of depth and size information are binocular cues and motion parallax. Here, the authors determine the efficacy of these cues to control prehension by presenting them in isolation from other visual cues. When only binocular cues were available, reaches showed normal scaling of the transport and grasp components with object distance and size. However, when only motion parallax was available, only the transport component scaled reliably. No additional increase in scaling was found when both cues were available simultaneously. Therefore, although equivalent information is available from binocular and motion parallax information, the latter may be of relatively limited use for the control of the grasp. Binocular disparity appears selectively important for the control of the grasp.