Stimulus generalization and the response-reinforcement contingency

Generalization gradients along a line-tilt continuum were obtained from groups of pigeons that had been trained to peck a key on different schedules of reinforcement. In Exp. I, gradients following training on a differential-reinforcement-of-low-rate (DRL) schedule proved to be much flatter than gradients following the usual 1-min variable interval (VI) training. In Exp. II, the value of the VI schedule itself was parametrically studied; Ss trained on long VI schedules (e.g., 4-min) produced much flatter gradients than Ss trained on short VI schedules (30-sec; 1-min). The results were interpreted mainly in terms of the relative control exerted by internal, proprioceptive cues on the different reinforcement schedules. Several implications of the results for other problems in the field of stimulus generalization are discussed.     

Similarity effects in visual working memory

Perceptual similarity is an important property of multiple stimuli. Its computation supports a wide range of cognitive functions, including reasoning, categorization, and memory recognition. It is important, therefore, to determine why previous research has found conflicting effects of inter-item similarity on visual working memory. Studies reporting a similarity advantage have used simple stimuli whose similarity varied along a featural continuum. Studies reporting a similarity disadvantage have used complex stimuli from either a single or multiple categories. To elucidate stimulus conditions for similarity effects in visual working memory, we tested memory for complex stimuli (faces) whose similarity varied along a morph continuum. Participants encoded 3 morphs generated from a single face identity in the similar condition, or 3 morphs generated from different face identities in the dissimilar condition. After a brief delay, a test face appeared at one of the encoding locations for participants to make a same/different judgment. Two experiments showed that similarity enhanced memory accuracy without changing the response criterion. These findings support previous computational models that incorporate featural variance as a component of working memory load. They delineate limitations of models that emphasize cortical resources or response decisions.     

Relations between classroom goal structures and students’ goal orientations in mathematics classes: When is a mastery goal structure adaptive?

The purpose of this study was to test possible interactions between mastery and performance goal structures in mathematics classrooms when predicting students’ goal orientations. More specifically, we tested if the degree of performance goal structure moderated the associations between mastery goal structure and students’ goal orientations. Participants were 1628 5th to 10th grade students from eight elementary and middle schools from one large city in Norway. The data were analyzed by means of regression analysis. The results showed that the association between a mastery goal structure in the mathematics classrooms and students’ personal goal orientations were significantly moderated by the degree of performance goal structure. This was true for all dimensions of goal orientation tested in this study.     

Is anaphoric reference cooperative?

Two experiments investigated whether the choice of anaphoric expression is affected by the presence of an addressee. Following a context sentence and visual scene, participants described a target scene that required anaphoric reference. They described the scene either to an addressee (Experiment 1) or without an addressee (Experiment 2). When an addressee was present in the task, participants used more pronouns and fewer repeated noun phrases when the referent was the grammatical subject in the context sentence than when it was the grammatical object and they used more pronouns when there was no competitor than when there was. They used fewer pronouns and more repeated noun phrases when a visual competitor was present in the scene than when there was no visual competitor. In the absence of an addressee, linguistic context effects were the same as those when an addressee was present, but the visual effect of the competitor disappeared. We conclude that visual salience effects are due to adjustments that speakers make when they produce reference for an addressee, whereas linguistic salience effects appear whether or not speakers have addressees.