The role of landmarks in cotton-top tamarin spatial foraging: evidence for geometric and non-geometric features

We report experiments on captive cotton-top tamarins (Saguinus oedipus) designed to explore two components of spatial foraging. First, do tamarins have the capacity to extract geometric information concerning the spatial relationship between a landmark and a piece of food located above or below it? Second, when tamarins use a landmark to find a target location, what non-geometric features of the landmark do they encode? To explore these problems, we created an artificial jungle environment and trained subjects to find food either above or below a target object (i.e., landmark). Once subjects successfully located the food, we transformed various features associated with the landmark, including its color, orientation, and shape; we also manipulated the landmark-food reward distance, the overall shape of the jungle, and the number and position of landmarks. Results showed that the tamarins' success in finding the food reward was not affected by landmark color, orientation, number, or overall shape of the jungle, suggesting that with respect to the particular test conditions, these features are not relevant to the representation of a landmark. Subjects also generalized to novel landmark-food distances, suggesting that they had integrated geometric (i.e., above/below) with non-geometric (i.e., color/shape) features. Performance was negatively affected by changes to the shape of the landmark, indicating that this feature is critical to the representation of a landmark. Accepted after revision: 7 August 2001 Electronic Publication     

Career decision-making difficulties of British and Chinese international university students

This study explored cultural and gender differences in career decision-making difficulties (CDMD) experienced by 109 British and 86 Chinese international university students, and the impact of cross-cultural adjustment on the CDMD of Chinese international students. Results showed no significant cultural differences in overall CDMD, and that the cross-cultural adjustment of Chinese participants was not correlated with their difficulty in career decision-making. Significant cultural differences on the sub-categories of the Career Decision-making Difficulties Questionnaire (e.g. Chinese participants were significantly less ready than British participants to make career decisions) and some significant gender differences (e.g. male participants generally experienced fewer difficulties than female participants in career decision-making) were identified. Age and degree level were negatively related to the level of difficulty the participants experienced in career decision-making. Implications for career counselling and future research directions are discussed.     

Transthyretin influences spatial reference memory

Transthyretin (TTR) is a plasma and cerebrospinal fluid carrier for thyroxine and retinol, described also to sequester the amyloid beta peptide. TTR levels have been described as decreased in the cerebrospinal fluid of patients with Alzheimer's disease. In order to investigate the role of TTR in learning and memory, we studied young adult and old TTR-null 129/Sv mice for cognitive performance. In the absence of TTR, 5-month-old mice display spatial reference memory impairment when compared to age-matched wild-type mice. Interestingly, while aging in wild-type mice is associated with a worsening reference memory performance, TTR-null mice show no further impairment with increasing age. As a result, no significant differences were found in this spatial reference task in old mice. Our data show that the absence of TTR seems to accelerate the poorer cognitive performance normally associated with aging.     

Measuring Subjective Quality of Life: A Survey to Porto’s Residents

The evaluation of the urban quality of life has been an important aspect of the research concerning the contemporary city and an increasingly support to urban planning and management. As part of a project to monitor the quality of life in the city of Porto, a survey of the resident population was conducted in order to study the citizens’ perceptions of their local quality of life and its evolution in recent years. The opinions of individuals on their level of satisfaction with various fields of the urban quality of life are systematised, as well as their integrated assessment. This analysis is complemented by a multivariate analysis that allows the grouping of the interviewees in large homogenous groups and their social and economic characterisation. Based on the results achieved, we try to highlight the usefulness of the qualitative analysis of the quality of life to support the definition of urban policies.

THIS ARTICLE HAS BEEN RETRACTED: Enumeration of objects and substances in non‐human primates: experiments with brown lemurs (Eulemur fulvus)

Both human infants and adult non‐human primates share the capacity to track small numbers of objects across time and occlusion. The question now facing developmental and comparative psychologists is whether similar mechanisms give rise to this capacity across the two populations. Here, we explore whether non‐human primates’ object tracking abilities are subject to the same constraints as those of human infants. In particular, we examine whether one primate species, the brown lemur (Eulemur fulvus), also fails to represent and enumerate objects when they behave non‐rigidly or non‐cohesively. We presented lemurs with a series of expectancy violation studies involving simple 1 + 1 addition events in which we varied the entities to be enumerated. Like infants, lemurs successfully enumerated the two objects when those objects were rigid, cohesive individuals, but failed to enumerate similar‐looking non‐rigid piles of sand. In contrast to human infants, however, lemurs successfully enumerated non‐cohesive objects that broke into multiple pieces. These results are discussed in light of recent theories about object processing in human infants and adults.     

Learning a foreign language: Effects of tact and listener instruction on the emergence of bidirectional intraverbals

We evaluated the effects of tact and listener instruction on the emergence of bidirectional intraverbal relations with 6 typically developing Brazilian children, using an adapted alternating treatment design with pretest and posttest probes. In listener instruction, participants selected pictures that corresponded to spoken foreign-language words. For tact instruction, children had to vocalize foreign words in the presence of the corresponding pictures. After meeting mastery criteria, bidirectional intraverbal tests assessed vocalizations in Portuguese (native language) following the presentation of the equivalent words in English (foreign language) and vice versa. Tact instruction consistently produced higher levels of emergent intraverbal responding compared to listener instruction, confirming results from previous studies.     

Functional analysis and intervention of perseverative speech in students with high-functioning autism and related neurodevelopmental disabilities

Although perseverative speech is a common characteristic of individuals with high-functioning neurodevelopmental disabilities, little is known about the operant functions of these verbalizations. We conducted analogue functional analyses of perseverative speech for 2 students using reinforcement contingencies that included alone, attention, control, escape, and tangible conditions. Results showed the following patterns: attention only (Charlotte) or multiply determined including an attention function (Paul). We then tested an intervention for perseverative speech maintained by social positive reinforcement that included differential reinforcement of alternative behavior and extinction of perseverative speech for 1 participant. The intervention reduced perseverative speech, but did not increase appropriate speech until we added a prompting component. We then replicated this three-component intervention with Paul. The results showed moderate to high decreases in levels of perseverative speech and increased appropriate verbalizations in both cases. The results systematically replicated the interventions of previous studies by adding a prompting component to the intervention.     

Attitudes toward hiring people with disabilities: A meta-cognitive approach to persuasion

Attitudes toward hiring people with disabilities are becoming critical for promoting diversity and egalitarianism within organizations. The few interventions designed to promote positive attitudes toward people with disabilities have relied on changing either the direction and/or the amount of thoughts people generate with regard to this discriminated, understudied group. In the present research, we examine the impact of a different psychological process of attitude change based on meta-cognition, or thinking about thinking. We used a meta-cognitive approach to changing prejudiced attitudes because thoughtful processes are often overlooked or denied with regard to this particular group. Specifically, we explored the impact of thought confidence on attitude change across two studies designed to change attitudes toward the incorporation of people with disabilities in companies. In each study, participants first generated either positive or negative thoughts about the proposal (thought valence manipulation). Then, the confidence in those thoughts was measured (Study 1) or manipulated (Study 2). In concert with the self-validation hypothesis, results showed that when thought confidence was relatively high (vs. low), thought valence had a greater impact on attitudes. Thus, thought valence was more predictive of attitudes when participants were confident in their thoughts. Specifically, confidence in thoughts enhanced persuasion for positive thoughts but reduced persuasion for negative thoughts. These findings provide insights into assessing effects of interventions aiming at improving attitudes toward the inclusion of minority groups in organizations.     

The Role of Co-Occurrence Statistics in Developing Semantic Knowledge

The organization of our knowledge about the world into an interconnected network of concepts linked by relations profoundly impacts many facets of cognition, including attention, memory retrieval, reasoning, and learning. It is therefore crucial to understand how organized semantic representations are acquired. The present experiment investigated the contributions of readily observable environmental statistical regularities to semantic organization in childhood. Specifically, we investigated whether co-occurrence regularities with which entities or their labels more reliably occur together than with others (a) contribute to relations between concepts independently and (b) contribute to relations between concepts belonging to the same taxonomic category. Using child-directed speech corpora to estimate reliable co-occurrences between labels for familiar items, we constructed triads consisting of a target, a related distractor, and an unrelated distractor in which targets and related distractors consistently co-occurred (e.g., sock-foot), belonged to the same taxonomic category (e.g., sock-coat), or both (e.g., sock-shoe). We used an implicit, eye-gaze measure of relations between concepts based on the degree to which children (N = 72, age 4–7 years) looked at related versus unrelated distractors when asked to look for a target. The results indicated that co-occurrence both independently contributes to relations between concepts and contributes to relations between concepts belonging to the same taxonomic category. These findings suggest that sensitivity to the regularity with which different entities co-occur in children's environments shapes the organization of semantic knowledge during development. Implications for theoretical accounts and empirical investigations of semantic organization are discussed.