The influence of chemical cues on the territorial prior residence effect in convict cichlids (cichlasoma nigrofasciatum Günther)

The importance of accumulated chemical cues on the occurrence of the territorial prior residence effect was investigated in two experiments using adult convict cichlids (Cichlasonul nigrofasciatum). In the first experiment, pairs of fish, matched on a number of criteria, were randomly assigned to three independent treatment conditions in which (1) the territorial marker (pot or clump of plants) was removed just prior to a direct encounter in the aquarium of the resident (pair member in whose aquarium the encounter took place) with accumulated chemical cues remaining intact; (2) the marker was removed, as well as the chemical cues; or (3) the marker was present, but the chemical cues were removed. Results showed that a significant prior residence effect occurred when the marker was present, but did not occur in either condition in which the marker was removed. A second experiment, in which the marker was removed and the gravel substrate altered, also did not reveal a signficant prior residence effect. Apparently, the territorial resident recognizes his territory by using certain visual cues, with accumulated chemical cues being neither necessary nor sufficient in this process.     

Within-session changes in operant responding when gerbils (Meriones unguiculatus) serve as subjects

Recent research has demonstrated that rate of responding frequently changes in a robust and systematic manner during experimental sessions in which organisms engage in operant responding. One potential cause for these changes in response rate is that levels of exploration change during experimental sessions and that high levels of exploration interfere with operant responding. Several studies have shown that gerbils (Meriones unguiculatus) explore at a constant rate during experimental sessions. The present study examined the response pattern produced by gerbils responding for food delivered by several simple schedules of reinforcement. Results indicated that robust changes (between 200 and 400%) in response rate occurred during the experimental sessions. These data argue against a role for exploration in the production of within-session changes in operant response rate.     

Within-session changes in operant responding when gerbils ( Meriones unguiculatus ) serve as subjects

Recent research has demonstrated that rate of responding frequently changes in a robust and systematic manner during experimental sessions in which organisms engage in operant responding. One potential cause for these changes in response rate is that levels of exploration change during experimental sessions and that high levels of exploration interfere with operant responding. Several studies have shown that gerbils (Meriones unguiculatus) explore at a constant rate during experimental sessions. The present study examined the response pattern produced by gerbils responding for food delivered by several simple schedules of reinforcement. Results indicated that robust changes (between 200 and 400%) in response rate occurred during the experimental sessions. These data argue against a role for exploration in the production of within-session changes in operant response rate. This material is based on work supported by the National Science Foundation under grant number IBN-9207346 awarded to FKM. The authors would like to thank Kelly S. Johnson, Samantha Swindell, and Dawn Miller for their help and useful suggestions concerning this project.     

Interruption of phonological coding in conduction aphasia

A case study of conduction aphasia, investigating single word repetition, phonological coding, and short-term memory, is reported. Evidence from intact adults suggests that repetition can occur through either a lexical route or a direct auditory-articulatory link. For this conduction aphasic, E.A., the direct link was impaired, although the lexical route could be used to produce accurate single word repetition. Several experiments demonstrated a significant impairment in the generation and maintenance of an abstract phonological code. The consequences of a disruption of phonological coding on speech perception and on verbal short-term memory are discussed.     

Single-word reading in college dyslexics

Recent studies of single-word processing in dyslexic populations have focused on the differential predictions made by ‘delay’ and ‘deviance’ models. Many experiments in this area have sought to determine whether the reading process in dyslexia is idiosyncratic or similar to processing in younger non-dyslexic readers. Most relevant research has, however, failed to take account of recent developments in theoretical models of reading. Furthermore, relatively little research has examined the reading behaviour of ‘highly compensated’ subjects, who achieve high-level academic qualifications despite their developmental dyslexia. The present paper examines such a population, and concludes that its single-word reading is governed by the same spelling-to-sound word characteristics as reading by other groups. The implications of the results for the deviance/delay hypothesis and for models of word naming are discussed.     

Social Density,Interpersonal Relationships,and Residential Crowding Stress1

Research has suggested that tripled rooms may be characterized by a coalition of two roommate(s) and a third, left-out rommate (i.e., the isolate) who is more vulnerable to crowding and control-related problems. The present study sought (1) to confirm the existence of two person coalitions in tripled rooms and (2) to further explore the mediating effects of interpersonal relationships on crowding stress and related problems. Thirty intact groups of roommates from doubled rooms (n= 60) and 39 intact groups of roommates from tripled rooms (n= 117) completed a set of surveys concerned with residential experiences. Results suggested that crowding stress previously associated with tripled residential settings may be mediated by interpersonal relationships; tripled residents who had negative interpersonal relationships with their roommates reported being more bothered by crowding, at both the beginning and end of the semester, than doubled residents who expressed negativity towards their roommate. Satisfaction with privacy was also influenced not only by the number of people with whom a resident shared a room, but also by the nature of the resident's interpersonal relationships with his/her roommate(s). Data also suggest that control-related problems may be a direct outcome of poor interpersonal relationships among inhabitants. Results also indicated that only a small percentage of tripled rooms were characterized by reciprocal, two person coalitions.     

Children's use ofGet passives

Children's use ofget in passivelike constructions was examined in this study. Fifty-eight children at three age levels were tested twice on imitation, comprehension, and production tasks. For the imitation and comprehension tasks, passive sentences withget were modeled in one instance and withbe in the other instance. On both tasks, children performed significantly better on theget items than on thebe items. For the production tasks, active sentences were used as the experimental stimuli. Among 928 production responses possible, children produced 423get passives and 6be passives. The frequency ofget passives increased with increasing age. Qualitative analyses were performed to determine agerelated changes in the pattern of linguistic strategies chosen. These data were consistent with predictions derived from a model of lexical directionality: Children used moreget thanbe passives and more truncated than full passives.     

Development of the appearance-reality distinction

Young children can express conceptual difficulties with the appearance-reality distinction in two different ways: (1) by incorrectly reporting appearance when asked to report reality (“phenomenism”); (2) by incorrectly reporting reality when asked to report appearance (“intellectual realism”). Although both phenomenism errors and intellectual realism errors have been observed in previous studies of young children's cognition, the two have not been seen as conceptually related and only the former errors have been taken as a symptom of difficulties with the appearance-reality distinction. Three experiments investigated 3- to 5-year-old children's ability to distinguish between and correctly identify real versus apparent object properties (color, size, and shape), object identities, object presence-absence, and action identities. Even the 3-year-olds appeared to have some ability to make correct appearance-reality discriminations and this ability increased with age. Errors were frequent, however, and almost all children who erred made both kinds. Phenomenism errors predominated on tasks where the appearance versus reality of the three object properties were in question; intellectual realism errors predominated on the other three types of tasks. Possible reasons for this curious error pattern were advanced. It was also suggested that young children's problems with the appearance-reality distinction may be partly due to a specific metacognitive limitation, namely, a difficulty in analyzing the nature and source of their own mental representations.