Trial spacing is a determinant of cue interaction

Four conditioned lick suppression experiments with rats examined the effect of trial spacing on cue interaction. Experiments 1 and 2 found overshadowing to be eliminated with massed compound stimulus-outcome pairings and the usual trial spacing effect to be reversed with compound acquisition trials. Experiment 3 found that whether acquisition compound-outcome pairings were massed or spaced determined the effect of posttraining extinction treatment. Extinction of the overshadowing cue reduced responding following massed training and increased responding following spaced training. Extinction of the context decreased responding following massed training. Experiment 4 found the conditioning and devaluation results to be associative and stimulus specific. These results are in accord with the extended comparator hypothesis (J. C. Denniston, H. I. Savastano, & R. R. Miller, 2001).     

Dissociable neural systems for recognizing emotions

This study tested the hypothesis that the recognition of emotions would draw upon anatomically separable brain regions, depending on whether the stimuli were static or explicitly conveyed information regarding actions. We investigated the hypothesis in a rare subject with extensive bilateral brain lesions, patient B., by administering tasks that assessed recognition and naming of emotions from visual and verbal stimuli, some of which depicted actions and some of which did not. B. could not recognize any primary emotion other than happiness, when emotions were shown as static images or given as single verbal labels. By contrast, with the notable exception of disgust, he correctly recognized primary emotions from dynamic displays of facial expressions as well as from stories that described actions. Our findings are consistent with the idea that information about actions is processed in occipitoparietal and dorsal frontal cortices, all of which are intact in B.'s brain. Such information subsequently would be linked to knowledge about emotions that depends on structures mapping somatic states, many of which are also intact in B.'s brain. However, one of these somatosensory structures, the insula, is bilaterally damaged, perhaps accounting for B.'s uniformly impaired recognition of disgust (from both static and action stimuli). Other structures that are damaged in B.'s brain, including bilateral inferior and anterior temporal lobe and medial frontal cortices, appear to be critical for linking perception of static stimuli to recognition of emotions. Thus the retrieval of knowledge regarding emotions draws upon widely distributed and partly distinct sets of neural structures, depending on the attributes of the stimulus.     

Hindsight bias: how knowledge and heuristics affect our reconstruction of the past

Once people know the outcome of an event, they tend to overestimate what could have been anticipated in foresight. Although typically considered to be a robust phenomenon, this hindsight bias is subject to moderating circumstances. In their meta-analysis, Christensen-Szalanski and Willham (1991) observed that the more experience people have with the task under consideration, the smaller is the resulting hindsight bias. This observation is one benchmark against which the explanatory power of process models of hindsight bias can be measured. Therefore, we used it to put the recently proposed RAFT model (Hoffrage, Hertwig, & Gigerenzer, 2000) to another test. Our findings were consistent with the "expertise effect." Specifically, we observed-using computer simulations of the RAFT model-that the more comprehensive people's knowledge is in foresight, the smaller is their hindsight bias. In addition, we made two counterintuitive observations: First, the relation between foresight knowledge and hindsight bias appears to be independent of how knowledge is processed. Second, even if foresight knowledge is false, it can reduce hindsight bias. We conclude with a discussion of the functional value of hindsight bias.     

A specific role for the human amygdala in olfactory memory

The medial temporal lobe is known to play a role in the processing of olfaction and memory. The specific contribution of the human amygdala to memory for odors has not been addressed, however. The role of this region in memory for odors was assessed in patients with unilateral amygdala damage due to temporal lobectomy (n = 20; 11 left, 9 right), one patient with selective bilateral amygdala damage, and in 20 age-matched normal controls. Fifteen odors were presented, followed 1 h later by an odor-name matching test and an odor-odor recognition test. Signal detection analyses showed that both unilateral groups were impaired in their memory for matching odors with names, these patients were not significantly impaired on odor-odor recognition. Bilateral amygdala damage resulted in severe impairment in both odor-name matching as well as in odor-odor recognition memory. Importantly, none of the patients were impaired on an auditory verbal learning task, suggesting that these findings reflect a specific impairment in olfactory memory, and not merely a more general memory deficit. Taken together, the data provide neuropsychological evidence that the human amygdala is essential for olfactory memory.     

Evidence for preserved emotional memory in normal older persons

Emotion has been shown to have a modulatory effect on declarative memory. Normal aging is associated with a decline in declarative memory, but whether aging might affect the influence of emotion on memory has not been established. To investigate this, we administered a task that provides a detailed assessment of emotional memory to 80 neurologically normal adults ranging in age from 35 to 85 years. Across ages, memory performance was found to be modulated by the emotional significance of stimuli in a comparable manner (improved memory for gist, compromised memory for visual detail), despite an overall decline in memory performance with increasing age. The results raise the interesting possibility that aging has a differential effect on hippocampal versus amygdala function.     

Circadian phase-shifted rats show normal acquisition but impaired long-term retention of place information in the water task

It is thought that circadian rhythms may influence learning and memory processes. However, research supporting this view does not dissociate a mnemonic impairment from other performance deficits. Furthermore, published reports do not specify the type of memory system influenced by the circadian system. The present study assessed the effects of phase shifting on acquisition and expression of place navigation in the water maze, a task sensitive to hippocampal dysfunction. The results showed that phase-shifting circadian rhythms in rats impaired the expression of place information on a retention test but not initial acquisition or encoding of place information. These results suggest that disruption of circadian rhythms may impair consolidation of previously encoded hippocampal place information.     

Is a picture worth a thousand words? Evidence from concept definitions by patients with semantic dementia

Nine patients with semantic dementia (the temporal lobe variant of frontotemporal dementia) were asked to define concrete concepts either from presentation of a picture of the object or from its spoken name. As expected, the patients with the most severe semantic impairment produced the least detailed definitions, and the quality of the definitions overall was significantly related to concept familiarity. Further analyses of the definitions were designed to assess two key theoretical aspects of semantic organization. (i) Do objects and their corresponding names activate conceptual information in two neuroanatomically separable (modality-specific) semantic systems? If so, then-apart from any expected commonality in performance attributable to factors such as concept familiarity-one would not predict striking item-specific similarities in a patient's picture- and word-elicited definitions. (ii) Do sensory/perceptual features and more associative/functional attributes of conceptual knowledge form two neuroanatomically separable subsystems? If so, then one would predict significant dissociations in the prominence of these two types of information in the patients' definitions. The results lead us to favor a model of the semantic system that is divided by attribute type but not by modality.     

The Relation between Formal and Informal Logic

The issue of the relationship between formal and informal logic depends strongly on how one understands these two designations. While there is very little disagreement about the nature of formal logic, the same is not true regarding informal logic, which is understood in various (often incompatible) ways by various thinkers. After reviewing some of the more prominent conceptions of informal logic, I will present my own, defend it and then show how informal logic, so understood, is complementary to formal logic.