Duration of cats' (Felis catus) working memory for disappearing objects

This study explored the duration of cats' working memory for hidden objects. Twenty-four cats were equally divided into four groups, which differed according to the type of visual cues displayed on and/or around the hiding boxes. During eight sessions, the four groups of cats were trained to locate a desirable object hidden behind one of the four boxes placed in front of them. Then, the cats were tested with retention intervals of 0, 10, 30 and 60 s. Results revealed no significant differences between the groups during training or testing. In testing, the cats' accuracy to locate the hidden object rapidly declined between 0 and 30 s but remained higher than chance with delays of up to 60 s. The analysis of errors also indicated that the cats searched as a function of the proximity of the target box and were not subjected to intertrial proactive interference. This experiment reveals that the duration of cats' working memory for disappearing objects is limited and the visual cues displayed on and/or around the boxes do not help the cats to memorize a hiding position. In discussion, we explore why the duration of cats' working memory for disappearing objects rapidly declined and compare these finding with those from domestic dogs. The irrelevance of visual cues displayed on and around the hiding boxes on cats' retention capacity is also discussed.     

Call recognition in chicks of the Australian brush-turkey (Alectura lathami)

Most birds rely on imprinting and experience with conspecifics to learn species-specific recognition cues. Australian brush-turkeys (Alectura lathami) do not imprint and form no bonds with parents. They hatch asynchronously, disperse widely and meet juvenile conspecifics at an unpredictable age. Nevertheless, in captivity, hatchlings respond to other chicks. A recent study, which involved the use of robotic models, found that chicks prefer to approach robots that emit specific visual cues. Here, we evaluated their response to acoustic cues, which usually play an important role in avian social cognition. However, in simultaneous choice tests, neither 2-day-old nor 9-day-old chicks preferred the choice arm with playback of either chick or adult conspecific calls over the arm containing a silent loudspeaker. Chicks of both age classes, however, scanned their surroundings more during chick playback, and the response was thus consistent in younger and older chicks. We also presented the chicks with robotic models, either with or without playback of chick calls. They did not approach the calling robot more than they did the silent robot, indicating that the combination of visual and acoustic cues does not evoke a stronger response. These results will allow further comparison with species that face similar cognitive demands in the wild, such as brood parasites. Such a comparative approach, which is the focus of cognitive ecology, will enable us to further analyse the evolution and adaptive value of species recognition abilities.     

The role of cues to differential absolute size in children's transitive inferences

To investigate the role that "nonlogical" cues might play in transitive inference, 6- and 7-year-olds were given a three-term transitive task in which perceptual cues to differential absolute size were either present or absent. Relationships between the taught premises and the relational information that was physically present were manipulated using four basic conditions: "congruent," "inverse," "pretended," or "persuaded." Both age groups showed identical overall premise memory, but the younger group tended to reason more on the basis of the perceptual information rather than on the successfully encoded premise information. Contrasts between the various conditions showed that categorical effects can be circumvented in three-term problems with appropriate controls, that there may be qualitative as well as quantitative differences in transitive inference with age, and that transitive inference is not based solely on memory. The findings also indicate that, although 7-year-olds are competent in "logic-based" transitive inference, they experience great difficulty on tasks involving pretend information.     

An infant chimpanzee (Pan troglodytes) follows human gaze

The ability of non-human primates to follow the gaze of other individuals has recently received much attention in comparative cognition. The aim of the present study was to investigate the emergence of this ability in a chimpanzee infant. The infant was trained to look at one of two objects, which an experimenter indicated by one of four different cue conditions: (1) tapping on the target object with a finger; (2) pointing to the target object with a finger; (3) gazing at the target object with head orientation; or (4) glancing at the target object without head orientation. The subject was given food rewards independently of its responses under the first three conditions, so that its responses to the objects were not influenced by the rewards. The glancing condition was tested occasionally, without any reinforcement. By the age of 13 months, the subject showed reliable following responses to the object that was indicated by the various cues, including glancing alone. Furthermore, additional tests clearly showed that the subject's performance was controlled by the "social" properties of the experimenter-given cues but not by the non-social, local-enhancing peripheral properties. Electronic Publication     

Solving spatial tasks with unaligned layouts: the difficulty of dealing with conflicting information

Previous research has shown that preschool children have difficulty using relational information in spatial tasks. The present study investigates whether this difficulty is due, in part, to children's inability to deal with situations of conflict where both objective and egocentric cues are available and point to different responses. Two studies were conducted to compare performance in the presence versus absence of conflicting cues. In Study 1, 40 four-year-olds had to locate an object in a single layout presented from different perspectives. In Study 2, 39 four-year-olds had to transfer locational information between two unaligned layouts. The presence of conflict significantly affected children's performance in both studies. The results are discussed in the context of similar findings in other cognitive domains.     

Conceptual accessibility and sentence production in a free word order language (Odawa)

The study reported here was conducted in the Algonquian language of Odawa (a.k.a. Ottawa), with the goal of gaining new insight into the ways that conceptual accessibility affects human sentence production. The linguistic characteristics of Odawa are quite different from those found in the languages most often examined by psycholinguists. The data obtained from the sentence production experiment reported here are thus relevant to production in a heretofore unexamined language. Moreover, the data inform broader theoretical issues, such as the extent to which sentence production can be considered as an incremental process, and the interaction of the various factors affecting conceptual accessibility. In addition, the study stands as evidence that experimental psycholinguistic research can and should be carried out in typologically diverse languages.     

Serial order and consonant-vowel structure in a graphemic output buffer model

We review features of the spelling errors of dysgraphic patients with "Graphemic Buffer Disorder" (GBD). We argue that the errors made by such patients suggest the breakdown of a system used to generate serial order in the output stages of spelling production, and we develop a model for this system based on an existing theory of sequential behaviour--"Competitive Queuing." We show that constraints on response categories may be straightforwardly applied during sequence production in such a model, and this enables us to account for the preservation of consonant-vowel status in the spelling errors of GBD patients. When the sequence generation process is disrupted by the addition of random noise the model shows the major features of GBD. The results are compared in detail against data from a number of patients.     

The effects of phrase-length order and scrambling in the processing of visually presented Japanese sentences

The present study investigated the effects of phrase length and scrambling in the processing of Japanese sentences. Reading times of short phrases, long phrases, verbs, and whole sentences, measured by the method of self-paced reading, did not differ in terms of phrase-length order and scrambling. In addition, four types of sentences constructed on the basis of phrase-length order and scrambling did not affect duration times of correctness decision-making for sentences. However, error rates differed between canonical and scrambled sentences regardless of phrase-length order. This result implies that scrambled sentences were harder to judge as correct sentences than canonical sentences. Thus, scrambling affects the appropriate integration of information, whereas phrase-length order is simply an indication of preference and not of cognitive processing. To explain the present result, the authors propose the configurational structure without movement, which predicts no difference in speed between the processing of canonical and scrambled sentences, apart from error rates.     

The dynamic functions of social cues during children's word learning

Children learn words in a social environment, facilitated in part by social cues from caregivers, such as eye-gaze and gesture. A common assumption is that social cues convey either perceptual or social information, depending on the age of the child. In this review of research on word learning and social cues during early childhood, we propose that (1) the functions of social cues are not categorically perceptual or social, and (2) social cues support word learning in four interdependent ways: by helping children to orient attention, extract relevant information, disambiguate referents, and understand others' referential intent. We conclude with specific recommendations for theory-building and suggest that the dynamic and complex functions of social cues need to be accounted for in any complete theory of word learning.     

Birth-order and sex differences in the frequency of referral of children for psychological treatment: A partial replication and extension

A previous study of two-child families by Lahey, Hammer, Crumrine, and Forehand (1980) found that firstborn children were more likely to be referred for psychological treatment than second-borns and that males were more likely to be referred than females. Furthermore, there was a significant interaction between these two variables. In the present study, a new sample of two-child families from the same clinic was studied, confirming the previous findings of significant birth-order and sex effects but not the interaction. Separate analyses indicated that both birth-order and sex effects were significant for children given externalizing diagnoses, but only the birth-order effect was significant for heterogeneous internalizing diagnoses. Similarly, an analysis of only children revealed a significant sex effect for externalizers but not internalizers. A combined sample of two-child families independent of diagnosis (N=425)suggests that there are reliable associations of birth order and sex, but not the interaction, with referral rates in two-child families. Referred children were significantly more likely to have a female sibling than would be expected by chance, regardless of birth order or sex, suggesting that these children may look more deviant by comparison to female, vs. male, siblings, thus increasing the likelihood of clinic referral. The potential utility of birth order and sex as demographic marker variables for etiological research is discussed.