An examination of the value of the generation effect for learning new material

The generation effect involves an improvement in memory when learners must complete or modify materials. Several researchers have suggested that this effect involves enhanced access to learners' existing memory representations; therefore, the effect should be less effective with meaningless, low meaningful, or unfamiliar material. In the present study, the authors conducted 4 experiments in which legal nonwords were used, and they found no generation effect. In another 2 experiments in which familiar clichés were contrasted with new sentences and with unfamiliar sentences from textbooks, the results showed a greatly reduced generation effect for the new, unfamiliar material. Those findings suggest that memory strategies that depend on the generation effect will have limited effectiveness when they are applied to new or unfamiliar material.     

Experimental tests of an attitudinal theory of the gender gap in voting

This research examined the hypothesis that gender gaps in voting stem from differences in the extent to which men and women agree with candidates' issue stances. Two initial experiments portraying candidates by their sex and attitudes and a third experiment that also included information about political party produced the predicted attitudinal gender-congeniality effect: Participants of each sex reported greater likelihood, compared with participants of the other sex, of voting for the candidate who endorsed positions typically favored more by their own sex than the other sex. In addition, this gender-congeniality effect was present among Republican and independent participants but absent among Democratic participants because Democratic men as well as women favored candidates who advocated the positions typically favored by women. Interpretation invoked the importance of group interest based on gender as an influence on women's voting.     

Gender differences in cardiovascular and hypothalamic-pituitary-adrenal axis responses to psychological stress in healthy older adult men and women

Gender differences in the neuroendocrine and cardiovascular response to psychological stress may contribute to the gender differences in the prevalence of diseases associated with hypothalamic-pituitary-adrenal (HPA) axis reactivity such as cardiovascular disease (CVD), diabetes and hypertension. We measured plasma ACTH, cortisol, heart rate (HR), and blood pressure (BP) responses in 8 men and 8 women (55-75 years) exposed to the Matt Stress Reactivity Protocol (MSRP), a psychological challenge. The MSRP elicited significant increases in HR, systolic-, and diastolic BP, ACTH and cortisol (all p<0.01). Men had significantly greater cortisol and diastolic BP responses compared to women (p<0.05). Additionally, a positive correlation between the ACTH and cortisol responses was only found in the males (r=0.71, p<0.05). There were no group differences in HR, systolic BP, or ACTH responses. We conclude, that among older adults, men respond to psychological stress with greater increases in cortisol, compared to women. This greater activation of the HPA axis could translate into an elevated risk for CVD, diabetes and hypertension and may be related to the higher prevalence of these diseases in males. Gender differences in brain structures and/or cognitive processes may be responsible for these sexually dimorphic stress responses.     

Perirhinal cortex lesions impair context aversion learning

Rats with perirhinal cortex lesions were compared with sham controls on a conditional discrimination in which saccharin was paired with LiCl in context 1, but paired with saline in context 2. Perirhinal-lesioned rats were slightly slower to acquire the discrimination but reached control levels by the end of acquisition. Both groups showed transfer to familiar tap water, consuming less in context 1 than in context 2. Unlike sham rats, perirhinal rats failed to show an aversion to context 1 on a place choice test. These data provide neuroanatomical support for the postulated difference between Pavlovian conditioning and conditional learning.     

Visual perspective taking for avatars in a Simon task

In modern digital applications, users often interact with virtual representations of themselves or others, called avatars. We examined how these avatars and their perspectives influence stimulus–response compatibility in a Simon task. Participants responded to light/dark blue stimuli with left/right key presses in the presence of a task-irrelevant avatar. Changes in stimulus–response compatibility were used to quantify changes in the mental representation of the task and perspective taking toward this avatar. Experiments 1 and 2 showed that perspective taking for an avatar occurred in orthogonal stimulus–response mappings, causing a compatibility effect from the avatar’s point of view. In the following two experiments we introduced a larger variety of angular disparities between the participant and avatar. In Experiment 3, the Simon effect with lateralized stimulus positions remained largely unaffected by the avatar, pointing toward an absence of perspective taking. In Experiment 4, after avatar hand movements were added in order to strengthen the participants’ sense of agency over the avatar, a spatial compatibility effect from the avatar’s perspective was observed again, and hints of the selective use of perspective taking on a trial-by-trial basis were found. Overall, the results indicate that users can incorporate the perspective of an avatar into their mental representation of a situation, even when this perspective is unnecessary to complete a task, but that certain contextual requirements have to be met.     

Knowledge level learning and the power law: A soar model of skill acquisition in scheduling

Zusammenfassung. Das hier vorgestellte Modell lernt graduell, Planungsaufgaben aus der Klasse der Maschinenbelegungsprobleme (job-shop-scheduling problems) zu lösen. Mit Hilfe des Chunking-Mechanismus von Soar wird episodisches Wissen über die Belegungsreihenfolge von Aufträgen auf Maschinen memoriert. Bei der Entwicklung des Modells wurden zahlreiche qualitative (z. B. Transfereffekte) und quantitative Befunde (z. B. Bearbeitungszeiten) aus einer früheren empirischen Untersuchung berücksichtigt. In einer Validierungsstudie wurden dieselben Aufgaben von 14 Probanden und dem Modell bearbeitet. Die Passung von Simulationsdaten und empirischen Ergebnissen fiel insgesamt gut aus. Allerdings löst das Modell die Aufgaben schneller und zeigt auch einen etwas besseren Lernverlauf als die Probanden. Das Modell liefert eine Erklärung für das Rauschen, das typischerweise bei Bearbeitungszeiten zu beobachten ist: es handelt sich um erworbenes Wissen, das mehr oder weniger gut und auch unterschiedlich häufig auf neue Situationen übertragen wird. Der Lernverlauf der Probanden entspricht nur für aggregierte Daten einer Potenzfunktion (power law). Der vorgestellte Mechanismus zeigt, wie ein symbolisches Modell der Informationsverarbeitung graduelle Verhaltensänderungen generiert und wie der offensichtliche Erwerb allgemeiner Prozeduren ohne explizites Lernen von deklarativen Regeln erfolgen kann. Es wird nahegelegt, daß es sich hier um die Modellierung einer Form impliziten Lernens handelt. Summary. The model presented here gradually learns how to perform a job-shop scheduling task. It uses Soar's chunking mechanism to acquire episodic memories about the order to schedule jobs. The model was based on many qualitative (e.g., transfer effects) and quantitative (e.g., solution time) regularities found in previously collected data. The model was tested with new data where scheduling tasks were given to the model and to 14 subjects. The model generally fit these data with the restrictions that the model performs the task (in simulated time) faster than the subjects, and its performance improves somewhat more quickly than the subjects' performance. The model provides an explanation of the noise typically found in problem solving times - it is the result of learning actual pieces of knowledge that transfer more or less to new situations but rarely by an average amount. Only when the data are averaged (i.e., over subjects) does the smooth power law appear. This mechanism demonstrates how symbolic models can exhibit a gradual change in behavior and how the apparent acquisition of general procedures can be performed without resorting to explicit declarative rule generation. We suggest that this may represent a type of implicit learning.     

The puzzle of language evolution

Linguistics must again concentrate on the evolutionary nature of language, so that language models are more realistic with respect to human natural languages and have a greater explanatory force. Multi-agent systems are proposed as a possible route to develop such evolutionary models and an example is given of a concrete experiment in the origins and evolution of word-meaning based on a multi-agent approach.     

Adults’ perception of native and nonnative vowels: Implications for the perceptual magnet effect

Two experiments were conducted to evaluate the perceptual magnet effect. In Experiment 1, Amer-ican English speakers representing diverse dialects were presented with a fine-grained set of stimuli (varying in just noticeable differences forF1 andF2) and indicated whether they heard “/i/” or “not /i/,” thus delimiting the /i/ portion of the vowel space for individual subjects. Then these same subjects selected their own /i/ prototype with a method-of-adjustment procedure. The data from this experiment were used to synthesize customized prototype and nonprototype stimulus sets for Experiment 2. In Experiment 2,24 of our original 37 subjects completed a discrimination task for each of three conditions, in which vector stimuli varied from the subject’s prototype, the nonprototype, or a foreign vowel (/y/) in 15-mel steps. Subjects displayed higher discrimination, as indexed byd′, for the nonprototype condition than they did for both the prototype and the foreign conditions. In addition, discrimination was better for variants further away from the referent in each condition. However, discrimination was not especially poor for stimuli close to subjects’ individual prototypes—a result that would have yielded the strongest support for the operation of a magnet effect. This negative finding, together with other aspects of our results, raises problems for any theory of vowel perception that relies solely on “one-size-fits-all” prototype representations.