Determinants of offline processing of visual information for the control of reaching movements

The authors investigated the use of visual feedback as a form of knowledge of results (KR) for the control of rapid (200-250 ms) reaching movements in 40 participants. They compared endpoint accuracy and intraindividual variability of a full-vision group (FV) with those of no-vision groups provided with KR regarding (a) the endpoint in numerical form, (b) the endpoint in visual form, or (c) the endpoint and the trajectory in visual form (DEL). The FV group was more accurate and less variable than were the no-vision groups, and the analysis of limb trajectory variability indicated that their superior performance resulted primarily from better movement planning rather than from online visual processes. The FV group outperformed the DEL group even though both groups were obtaining the same amount of spatial visual information from every movement. That finding suggests that the effectiveness with which visual feedback is processed offline is not a simple function of the amount of visual information available, but depends on how that information is presented.     

Reinforcement value and substitutability of sucrose and wheel running: implications for activity anorexia

Choice between sucrose and wheel-running reinforcement was assessed in two experiments. In the first experiment, ten male Wistar rats were exposed to concurrent VI 30 s VI 30 s schedules of wheel-running and sucrose reinforcement. Sucrose concentration varied across concentrations of 2.5, 7.5, and 12.5%. As concentration increased, more behavior was allocated to sucrose and more reinforcements were obtained from that alternative. Allocation of behavior to wheel running decreased, but obtained wheel-running reinforcement did not change. Overall, the results suggested that food-deprived rats were sensitive to qualitative changes in food supply (sucrose concentration) while continuing to defend a level of physical activity (wheel running). In the second study, 15 female Long Evans rats were exposed to concurrent variable ratio schedules of sucrose and wheel-running, wheel-running and wheel-running, and sucrose and sucrose reinforcement. For each pair of reinforcers, substitutability was assessed by the effect of income-compensated price changes on consumption of the two reinforcers. Results showed that, as expected, sucrose substituted for sucrose and wheel running substituted for wheel running. Wheel running, however, did not substitute for sucrose; but sucrose partially substituted for wheel running. We address the implications of the interrelationships of sucrose and wheel running for an understanding of activity anorexia.     

Event plausibility does not determine children's false memories

In this paper we ask how the plausibility of an event affects the likelihood that children will develop a false memory for it. Over three interviews 6-year-olds and 10-year-olds were shown two true photos and two false photos-a plausible and less plausible event-and reported what they could remember about those events. Children also rated their confidence that the events happened, and how much they could remember about the events. By the final interview, within each age group, there were no differences in children's confidence ratings for the two false events. In addition, within each age group, the rate of false memories was the same for each event; across age groups, younger children developed more false memories than older children.     

Executive function is necessary for perspective selection,not Level-1 visual perspective calculation: Evidence from a dual-task study of adults

Previous research suggests that perspective-taking and other “theory of mind” processes may be cognitively demanding for adult participants, and may be disrupted by concurrent performance of a secondary task. In the current study, a Level-1 visual perspective task was administered to 32 adults using a dual-task paradigm in which the secondary task tapped executive function. Results suggested that the secondary task did not affect the calculation of perspective, but did affect the selection of the relevant (Self or Other) perspective for a given trial. This is the first direct evidence of a cognitively efficient process for “theory of mind” in adults that operates independently of executive function. The contrast between this and previous findings points to a distinction between simple perspective-taking and the more complex and cognitively demanding abilities more typically examined in studies of “theory of mind”. It is suggested that these findings may provide a parsimonious explanation of the success of infants on ‘indirect’ measures of perspective-taking that do not explicitly require selection of the relevant perspective.     

Resolution of activated background information in text comprehension

The present experiments explored the resolution of activated background information in text comprehension. In Experiment 1, participants read passages that contained an elaboration section that was either consistent or qualified (inconsistent but then corrected to be consistent) with respect to the subsequently presented target sentence (see O'Brien et al., 1998). However, the experiment used two target sentences, and several filler sentences were inserted between the first and second target sentence. The results showed that the reading times for the first target sentence in the qualified elaboration version were significantly longer than those in the consistent elaboration version. These were consistent with O'Brien's study, and further indicated that the basic process captured by the memory-based view appears to generalize to the Chinese reader better than does the here-and-now view. More importantly, the results showed that the reading times for the second target sentence in the qualified elaboration version were as long as those in the consistent elaboration version. These further indicated that the activation of background information not only maintained the coherence of the text, but also allowed for the relevant information to be updated, resulting in a unified information set. When the information was reactivated during ongoing reading, it would be in the form of unified information. In Experiment 2, the first target sentence in each passage from Experiment 1 was converted to a filler sentence, and the second target sentence became the target sentence. The results of Experiment 2 showed that the reading times for the target sentence in the qualified elaboration version were significantly longer than those for the consistent elaboration version. These indicated that the delay between the target sentences and the elaboration section was not responsible for the lack of differences in Experiment 1, and confirmed the conclusion of Experiment 1.     

Cross-count identity,distinctness, and the theory of internal and external relations

Baxter (Australas J Philos 79:449–464, 2001) proposes an ingenious solution to the problem of instantiation based on his theory of cross-count identity. His idea is that where a particular instantiates a universal it shares an aspect with that universal. Both the particular and the universal are numerically identical with the shared aspect in different counts. Although Baxter does not say exactly what a count is, it appears that he takes ways of counting as mysterious primitives against which different numerical identities are defined. In contrast, I defend the idea—suggested, though not quite endorsed, by Baxter himself—that counts are independent dimensions of numerical identity. Different ways of counting are explained by the existence of these different sorts of identity (i.e., counts). For the instantiation of a universal by a particular, I propose one dimension concerned with the individuation of particulars (the p-count) and another dimension concerned with the individuation of universals (the u-count). On that basis, I give a clear definition of cross-count identity that explains its asymmetrical nature (i.e., the fact that particulars instantiate universals, but not vice versa). I extend the theory to a third dimension—that of time, or the t-count—and thereby defend Baxter’s ideas on change, and the contingency of instantiation. Baxter (Mind 97(388):575–582, 1988; Australas J Philos 79:449–464, 2001) proposes the related idea of composition as (cross-count) identity. Parts are individually cross-count identical with the wholes that they constitute, and they collectively share all aspects across counts with those wholes. I propose an innovation by which totality is shared distinctness across counts. The theory applies to both the totality of particulars that instantiate any given universal, and the totality of parts that constitute any given whole. I argue that this has several advantages over Armstrong’s view, which is based on a dubious external totalling relation. I also argue that Armstrong’s theory of numbers (or quantities) as internal relations ought to be rejected in favour of an account based on identity and distinctness. The paper concludes with a careful analysis of external relations in Baxter’s framework. I argue that we must recognise one further dimension of identity in order to differentiate between, e.g., the aspects of Abelard insofar as he loves Heloise and Abelard insofar as he loves Isobel. Each of these aspects is identical with Abelard and identical with loving-by, yet they must be in some way distinct. I therefore propose the r-count, in which multiple distinct relational properties are the very same relation (-part). The existence of these four independent dimensions explains the fact that particulars, universals, relations, and times are fundamentally different sorts of things in the ontology. Each is individuated with respect to a different dimension of identity.     

Backward recall and benchmark effects of working memory

Working memory was designed to explain four benchmark memory effects: the word length effect, the irrelevant speech effect, the acoustic confusion effect, and the concurrent articulation effect. However, almost all research thus far has used tests that emphasize forward recall. In four experiments, we examine whether each effect is observable when the items are recalled in reverse order. Subjects did not know which recall direction would be required until the time of test, ensuring that encoding processes would be identical for both recall directions. Contrary to predictions of both the primacy model and the feature model, the benchmark memory effect was either absent or greatly attenuated with backward recall, despite being present with forward recall. Direction of recall had no effect on the more difficult conditions (e.g., long words, similar-sounding items, items presented with irrelevant speech, and items studied with concurrent articulation). Several factors not considered by the primacy and feature models are noted, and a possible explanation within the framework of the SIMPLE model is briefly presented.     

Short‐term and working memory: Past,progress, and prospects

Abstract

The role of current personal experience in understanding of word meaning was investigated in a patient, WM, who suffers from semantic dementia. The study was prompted by the observation that WM, despite being severely impaired on formal tests of word comprehension and naming, retained a range of vocabulary pertaining to her daily life. If autobiographical experience has a general facilitatory effect, then this should affect which concepts are retained and which lost, but not influence the quality of that conceptual knowledge. Conversely, if personal autobiography has a direct role in investing concepts with meaning, then WM's understanding of nominal terms that she uses spontaneously in conversation ought not to be normal, but should be constrained by the autobiographical context in which she uses those terms. WM could define nouns and noun phrases drawn from her conversational vocabulary, but her definitions had a markedly autobiographical quality. Moreover, WM was extremely impaired in her ability to define new noun phrases, constructed by combining words from her conversational vocabulary (e.g. “dog licence”, constructed from “driving licence” and “dog” “oil field” constructed from “oil” and “field”). It was concluded that WM does not have normal conceptual understanding of nouns and noun phrases that she uses appropriately in conversation. Her understanding is narrow and autobiographically constrained. The findings, which suggest an interactive relationship between autobiographical and semantic memory, have implications for understanding of the progressive breakdown of semantic knowledge.     

Recollection deficits in dysphoric mood: An effect of schematic models and executive mode?

Depression and dysphoric mood states are often accompanied by quantitative or qualitative shifts in performance across a range of retention tasks. This study focuses on the recollection of both autobiographical events and word lists in dysphoric states. Recollection occurs when people are aware of some contextual detail allied to the encoding experience. This study establishes the presence of a recollection deficit in dysphoria in two distinct paradigms. In both autobiographical recall and in recognition memory, recollection in a dysphoric group was at lower levels than recollection in matched controls. The study examines the hypothesis that the extent of recollection is influenced by two factors: (1) the degree of differentiation of schematic mental models; and (2) the executive mode that predominates when memory tasks are carried out, with the latter assumed to be altered by rumination. The relationship between responses based on recollection and alternative mnemonic responses could be predicted by measures of these two factors. The results are discussed in terms of the Interacting Cognitive Subsystems model (Teasdale & Barnard, 1993) and the perspective it offers on the relationship between meaning systems and executive functions (Barnard, 1999).     

The effects of local and global processing orientation on eyewitness identification performance

Recent work has demonstrated that performance on a simultaneous target-present photographic line-up can be enhanced by prior global processing orientation, and hindered by prior local processing orientation induced by processing Navon letter stimuli. A series of studies explore the generality of this processing bias effect using either videotaped scenarios or live interactions. Five experiments demonstrate that these effects are seen across a range of test stimuli, test formats, and test instructions. These data inform the processes engaged in by witnesses when making line-up identifications and indicate that it may be possible to improve the accuracy of witnesses making such judgements.