The differentiation of response numerosities in the pigeon

Two experiments examined how pigeons differentiate response patterns along the dimension of number. In Experiment 1, 5 pigeons received food after pecking the left key at least N times and then switching to the right key (Mechner's Fixed Consecutive Number schedule). Parameter N varied across conditions from 4 to 32. Results showed that run length on the left key followed a normal distribution whose mean and standard deviation increased linearly with N; the coefficient of variation approached a constant value (the scalar property). In Experiment 2, 4 pigeons received food with probability p for pecking the left key exactly four times and then switching. If that did not happen, the pigeons still could receive food by returning to the left key and pecking it for a total of at least 16 times and then switching. Parameter p varied across conditions from 1.0 to .25. Results showed that when p= 1.0 or p=.5, pigeons learned two response numerosities within the same condition. When p=.25, each pigeon adapted to the schedule differently. Two of them emitted first runs well described by a mixture of two normal distributions, one with mean close to 4 and the other with mean close to 16 pecks. A mathematical model for the differentiation of response numerosity in Fixed Consecutive Number schedules is proposed.     

Testing the Δ-∑ hypothesis in the suboptimal choice task: Same delta with different probabilities of reinforcement

In a concurrent-chain procedure, pigeons choose between 2 initial-link stimuli; one is followed by terminal link stimuli that signal reliably whether food will be delivered after a delay; the other is followed by terminal link stimuli that do not signal whether food will be delivered after the delay. Pigeons prefer the former alternative even when it yields a lower overall probability of food. Recently, we proposed the Delta-Sigma (∆-∑) hypothesis to explain the effect: Preference depends on the difference (∆) between the reinforcement probabilities associated with the terminal link stimuli, and the overall probability of reinforcement (∑) associated with the alternative. The hypothesis predicts that, for constant ∑, animals should prefer alternatives with greater ∆ values regardless of the specific probabilities of reinforcement that determine ∆. In 2 experiments, we tested this prediction by comparing a ∆ = .5 against a ∆ = 0 alternative, with the former obtained with different pairs of reinforcement probabilities across conditions. The results supported the hypothesis when the 2 probabilities defining ∆ were significantly greater than 0, but not when one of them was close to 0. The results challenge our theoretical accounts of suboptimal choice and the variables considered to determine pigeons’ preference.     

A lexical database for spanish-speaking children

This article presents a computerized database of words for use in experimental research in cognitive psychology and psycholinguistics. The data are based on the oral vocabulary of 200 Spanish-speaking children aged from 11.16 to 49.16 months. The database includes 15,428 Spanish words (tokens) and comprises 1,259 different words (types). It provides information about age of acquisition, orthography, grammar, semantics, and frequency.     

Scaling the information processing demands of occupations

The purpose of this study was to provide additional validity evidence for a model of person–environment fit based on polychronicity, stimulus load, and information processing capacities. In this line of research the confluence of polychronicity and information processing (e.g., the ability of individuals to process stimuli from the environment along five dimensions of information load, interpersonal load, change load, time structure, and activity structure) is applied to the occupational environment. Using magnitude estimation scaling, college students in the United States and Portugal rated 42 occupations across five information processing demand characteristics. Results indicated that occupations could be differentiated by the information load conditions, thus producing a profile of information processing demand characteristics unique to each of the occupations tested. Additional findings provided evidence for the validity of the scaled occupational values; ratings differed reliably across Holland categories, were fairly consistent across the two cultural groups, and showed expected relationships with salary and educational level.     

Relative versus absolute stimulus control in the temporal bisection task

When subjects learn to associate two sample durations with two comparison keys, do they learn to associate the keys with the short and long samples (relational hypothesis), or with the specific sample durations (absolute hypothesis)? We exposed 16 pigeons to an ABA design in which phases A and B corresponded to tasks using samples of 1 s and 4 s, or 4 s and 16 s. Across phases, we varied the mapping between the samples and the keys. For group Relative, short and long samples were always associated with the same keys (e.g., Phase A: ‘1s→ Left, 4s→ Right''; Phase B: ‘4s→ Left, 16s→ Right''); for group Absolute, the 4-s sample was associated always with the same key (e.g., Phase A: ‘1s→ Left, 4s→ Right''; Phase B: ‘16s→ Left, 4s→ Right’). If temporal control is relational, group Relative should learn the new task faster than group Absolute, but if temporal control is absolute, the opposite should occur. We compared the results with the predictions of the Learning-to-Time (LeT) model, which accounts for temporal discrimination in terms of absolute stimulus control and stimulus generalization. The acquisition curves of the two groups were generally consistent with LeT and therefore more consistent with the absolute than the relative hypothesis.     

Terrorists and victims. Infrahumanization of Moroccans after 11-M

Infrahumanization studies have verified that most people attribute more secondary emotions to the ingroup than to the outgroup. However, these results may vary with changing contexts. The main objective of this study was to investigate the infrahumanization of Moroccans, depending on the context, after the 11-M attacks and seven years later. For this purpose, variations that occur in the allocation of essential human qualities--secondary emotions--were analyzed by activating images of outgroup members in two opposite contexts: Guilty of the terrorist attack or its victim. The results show that the infrahumanization of the Moroccans in the perpetrator context does not change significantly with regard to the control group. However, infrahumanization does not take place when Moroccans are associated with a victim context, though only immediately after the terrorist attack, because seven years later, this effect disappears.     

An exploratory assessment of theory of mind and psychological impairment in patients with bulimia nervosa

This study aimed to investigate psychosocial functioning and different dimensions of theory of mind (ToM) in people with bulimia nervosa (BN) and Eating Disorder Not Otherwise Specified‐BN type (EDNOS‐BN). Psychosocial functioning and ToM were assessed in a sample of young adult females, 16 BN and 16 EDNOS‐BN outpatients and 16 healthy controls (HCs). They were assessed using the Eating Disorder Inventory‐Symptom Checklist‐2 (EDI‐2 SC) for evaluating psychological traits associated with eating disorders; the Symptom Checklist‐90‐Revised (SCL‐90‐R) for evaluating psychopathological status; and the Theory of Mind Assessment Scale (Th.o.m.a.s.), a semi‐structured interview aimed at assessing a person's different dimensions of ToM. The BN and EDNOS‐BN groups exhibited worse performance than the control group on all dimensions of the SCL‐90‐R, and on all dimensions of the EDI‐2 SC. The only difference for perfectionism was that BN obtained higher scores than EDNOS‐BN group. Our results also revealed an impairment of third‐person and second‐order ToM in patients with bulimia (BN and EDNOS‐BN) with respect to control subjects. These preliminary data have important implications for future empirical work, in that they provide valuable information regarding the importance of investigating the various facets of ToM ability separately, in order to provide a more detailed profile of ToM functioning in the clinical samples.     

Sexual Harassment and its Impact for Women Officers and Cadets in the Swedish Armed Forces

We examined the incidence, dimensions, and impact of sexual harassment on women officers and cadets in the Swedish military (N = 324). We expected that harassment rates for direct measures would be lower than for indirect measures; hostile environment harassment would be more prevalent than quid pro quo harassment; and harassment would negatively influence women's job-related outcomes and their psychological and physical health. We found that harassment rates for direct measures were lower than indirect measures; hostile environment harassment was more prevalent than quid pro quo harassment; and harassment was associated with decreased job satisfaction, organizational commitment, work group effectiveness, and psychological and physical health. We discuss the theoretical, methodological, and practical implications of our findings for studying harassment across cultures.