Unit price and choice in a token-reinforcement context

Pigeons were exposed to multiple and concurrent second-order schedules of token reinforcement, with stimulus lights serving as token reinforcers. Tokens were produced and exchanged for food according to various fixed-ratio schedules, yielding equal and unequal unit prices (responses per unit food delivery). On one schedule (termed the standard schedule), the unit price was held constant across conditions. On a second schedule (the alternative schedule), the unit price was either the same or different from the standard. Under conditions with unequal unit prices, near-exclusive preference for the lower unit price was obtained. Under conditions with equal unit prices, the direction and degree of preference depended on ratio size (number of responses per exchange period). When this ratio differed, strong preferences for the smaller ratio were observed. When this ratio was equal, preferences were nearer indifference. Response rates on the multiple schedule were generally consistent with the preference data in showing sensitivity to ratio size. Results are discussed in terms of a unit-price model that includes handling and reinforcer immediacy as additional costs. On the whole, results show that preferences were determined primarily by delay to the exchange period.     

Different types of environmental enrichment have discrepant effects on spatial memory and synaptophysin levels in female mice

Environmental enrichment paradigms that incorporate cognitive stimulation, exercise, and motor learning benefit memory and synaptic plasticity across the rodent lifespan. However, the contribution each individual element of the enriched environment makes to enhancing memory and synaptic plasticity has yet to be delineated. Therefore, the current study tested the effects of three of these elements on memory and synaptic protein levels. Young female C57BL/6 mice were given 3h of daily exposure to either rodent toys (cognitive stimulation) or running wheels (exercise), or daily acrobatic training for 6 weeks prior to and throughout behavioral testing. Controls were group housed, but did not receive enrichment. Spatial working and reference memory were tested in a water-escape motivated radial arm maze. Levels of the presynaptic protein synaptophysin were then measured in frontoparietal cortex, hippocampus, striatum, and cerebellum. Exercise, but not cognitive stimulation or acrobat training, improved spatial working memory relative to controls, despite the fact that both exercise and cognitive stimulation increased synaptophysin levels in the neocortex and hippocampus. These data suggest that exercise alone is sufficient to improve working memory, and that enrichment-induced increases in synaptophysin levels may not be sufficient to improve working memory in young females. Spatial reference memory was unaffected by enrichment. Acrobat training had no effect on memory or synaptophysin levels, suggesting a minimal contribution of motor learning to the mnemonic and neuronal benefits of enrichment. These results provide the first evidence that different elements of the enriched environment have markedly distinct effects on spatial memory and synaptic alterations.     

Inhibition of irrelevant category–response mappings

When switching tasks, performance tends to be worse for n – 2 repetitions than with n – 2 switches. This n – 2 repetition cost has been hypothesized to reflect task-set inhibition: specifically, inhibition of irrelevant category–response mappings involved in response selection. This hypothesis leads to divergent predictions for situations in which all tasks involve the same stimulus categories: An n – 2 repetition cost is predicted when response sets differ across tasks, but not when the response set stays the same. The authors tested these predictions by having subjects perform relative judgements with different reference points. In Experiment 1, the stimulus categories were the same across reference points, but the response set either differed or stayed the same (the multiple- and single-mapping conditions, respectively). An n – 2 repetition cost was found in the multiple-mapping condition but not in the single-mapping condition. Experiment 2 provided evidence against the possibility that these divergent effects reflected differences in memory load. These findings confirm predictions that link n – 2 repetition costs to inhibition of irrelevant category–response mappings.     

More is still not better: Testing the perturbation model of temporal reference memory across different modalities and tasks

The ability of the perturbation model (Jones & Wearden, 2003) to account for reference memory function in a visual temporal generalization task and auditory and visual reproduction tasks was examined. In all tasks the number of presentations of the standard was manipulated (1, 3, or 5), and its effect on performance was compared. In visual temporal generalization the number of presentations of the standard did not affect the number of times the standard was correctly identified, nor did it affect the overall temporal generalization gradient. In auditory reproduction there was no effect of the number of times the standard was presented on mean reproductions. In visual reproduction mean reproductions were shorter when the standard was only presented once; however, this effect was reduced when a visual cue was provided before the first presentation of the standard. Whilst the results of all experiments are best accounted for by the perturbation model there appears to be some attentional benefit to multiple presentations of the standard in visual reproduction.     

Local and global reference frames for environmental spaces

Two experiments examined how locations in environmental spaces, which cannot be overseen from one location, are represented in memory: by global reference frames, multiple local reference frames, or orientation-free representations. After learning an immersive virtual environment by repeatedly walking a closed multisegment route, participants pointed to seven previously learned targets from different locations. Contrary to many conceptions of survey knowledge, local reference frames played an important role: Participants performed better when their body or pointing targets were aligned with the local reference frame (corridor). Moreover, most participants turned their head to align it with local reference frames. However, indications for global reference frames were also found: Participants performed better when their body or current corridor was parallel/orthogonal to a global reference frame instead of oblique. Participants showing this pattern performed comparatively better. We conclude that survey tasks can be solved based on interconnected local reference frames. Participants who pointed more accurately or quickly additionally used global reference frames.     

Reference groups: A missing link in career studies

Careers unfold within and are bound by multiple social contexts. Newer career concepts have postulated a growing need for personal agency in overcoming structural constraints, especially organizational and occupational boundaries. As a consequence, research has focused more on the individual than on contextual factors. In order to answer recent criticism of this unbalanced view we argue that the impact of reference groups needs to be better understood, both as social drivers of agentic behavior and as social constraints that, for instance, reduce the permeability of boundaries. Drawing on identity theories and social network literature we suggest a classification of reference groups in which social domains (e.g., organization, occupation, family, friends), types of groups (known people, abstract social categories), and functions (normative, comparative, supportive) are distinguished. The reference group classification is employed to discuss extant career research and to propose three directions for future research: a) Fuller consideration of different social domains beyond the employing organization for a more complete understanding of social influences in contemporary careers; b) exploration of the possibly growing relevance of abstract social categories as referents, especially for subjective career success; and c) systematic analysis of the interaction between normative, comparative, and supportive functions of individuals' social networks. Across these themes, possible negative influences of reference groups and effects of imposed rather than chosen referents are also to be considered. Implications of the suggested research for better understanding the interaction between structure and agency in shaping careers and career identity are discussed.     

How Cognitive Load Influences Speakers' Choice of Referring Expressions

We report on two experiments investigating the effect of an increased cognitive load for speakers on the choice of referring expressions. Speakers produced story continuations to addressees, in which they referred to characters that were either salient or non‐salient in the discourse. In Experiment 1, referents that were salient for the speaker were non‐salient for the addressee, and vice versa. In Experiment 2, all discourse information was shared between speaker and addressee. Cognitive load was manipulated by the presence or absence of a secondary task for the speaker. The results show that speakers under load are more likely to produce pronouns, at least when referring to less salient referents. We take this finding as evidence that speakers under load have more difficulties taking discourse salience into account, resulting in the use of expressions that are more economical for themselves.     

廉价的优越感：社会排斥如何影响新奢侈品的消费

本研究从消费者社会需求层面,探讨在中国新奢侈品会给哪些人带来优越感,什么样的产品可以带来优越感,以及为何会带来优越感等问题。本研究使用一个混合设计的实验,结果发现：（1）相比较非社会排斥状态,社会排斥状态增加了消费者的身份消费需求。（2）在产品炫耀性大时,相比较传统大众产品和奢侈品,社会排斥增加了消费者对新奢侈品的购买意愿。而在产品炫耀性小时,社会排斥的影响不显著;（3）社会排斥、产品种类和产品炫耀性三者的交互作用影响消费者购买意愿的中介变量是消费者感知的产品身份价格比。结论表明,相比较传统大众产品和奢侈品,炫耀性新奢侈品以相对低的价格满足了社会排斥消费者的身份消费需求,为他们提供了一个获得优越感的渠道。     

Assessing the Incremental Algorithm: A Response to Krahmer et al.

This response discusses the experiment reported in Krahmer et al.’s Letter to the Editor of Cognitive Science. We observe that their results do not tell us whether the Incremental Algorithm is better or worse than its competitors, and we speculate about implications for reference in complex domains, and for learning from ‘‘normal” (i.e., non‐semantically‐balanced) corpora.