Memory span and general intelligence: A latent-variable approach

There are several studies showing that working memory and intelligence are strongly related. However, working memory tasks require simultaneous processing and storage, so the causes of their relationship with intelligence are currently a matter of discussion. The present study examined the simultaneous relationships among short-term memory (STM), working memory (WM), and general intelligence (g). Two hundred and eight participants performed six verbal, quantitative, and spatial STM tasks, six verbal, quantitative, and spatial WM tasks, and eight tests measuring fluid, crystallized, spatial, and quantitative intelligence. Especial care is taken to avoid misrepresenting the relations among the constructs being studied because of specific task variance. Structural equation modelling (SEM) results revealed that (a) WM and g are (almost) isomorphic constructs, (b) the isomorphism vanishes when the storage component of WM is partialed out, and (c) STM and WM (with its storage component partialed out) predict g.     

人口性别比例失衡对人类行为的影响

男女比例协调本是自然进化的规律。可在我国, 人口性别比例失调的现象日趋严重, 深入理解这一现象对社会产生何种影响已经成为一件刻不容缓的工作。进化心理学和社会人口学这两个领域近年来分别开展了一系列与此问题相关的研究, 从性选择、择偶、婚姻、亲本投资、暴力行为和经济行为六个方面全面研究人口性别比例对人类行为的影响。     

Habituation in Aplysia: The Cheshire Cat of neurobiology

The marine snail, Aplysia californica, is a valuable model system for cell biological studies of learning and memory. Aplysia exhibits a reflexive withdrawal of its gill and siphon in response to weak or moderate tactile stimulation of its skin. Repeated tactile stimulation causes this defensive withdrawal reflex to habituate. Both short-term habituation, lasting <30 min, and long-term habituation, which can last >24 h, have been reported in Aplysia. Habituation of the withdrawal reflex correlates with, and is in part due to, depression of transmission at the monosynaptic connection between mechanoreceptive sensory neurons and motor neurons within the abdominal ganglion. Habituation-related short-term depression of the sensorimotor synapse appears to be due exclusively to presynaptic changes. However, changes within the sensory neuron, by themselves, do not account for more persistent depression of the sensorimotor synapse. Recent behavioral work suggests that long-term habituation in Aplysia critically involves postsynaptic processes, specifically, activation of AMPA- and NMDA-type receptors. In addition, long-term habituation requires activity of protein phosphatases, including protein phosphatases 1, 2A, and 2B, as well as activity of voltage-dependent Ca²⁺ channels. Cellular work has succeeded in demonstrating long-term, homosynaptic depression (LTD) of the sensorimotor synapse in dissociated cell culture and, more recently, LTD of the glutamate response of isolated motor neurons in culture (“hemisynaptic” LTD). These in vitro forms of LTD have mechanistic parallels to long-term habituation. In particular, homosynaptic LTD of the sensorimotor synapse requires elevated intracellular Ca²⁺ within the motor neuron, and hemisynaptic LTD requires activity of AMPA- and NMDA-type receptors. In addition, activation of group I and II metabotropic glutamate receptors (mGluRs) can induce hemisynaptic LTD. The demonstration of LTD in vitro opens up a promising new avenue for attempts to relate long-term habituation to cellular changes within the nervous system of Aplysia.     

The efficacy of a short version of a cognitive-behavioral treatment followed by booster sessions for binge eating disorder

This waitlist-controlled study evaluated the efficacy of a short version of a group CBT for BED followed by booster sessions after the active treatment phase. Thirty-six females with BED were randomly assigned to CBT (eight weekly sessions during active treatment plus five booster sessions during follow-up) or a waitlist condition. At the end of the active treatment, binge eating was significantly reduced relative to waitlist. Furthermore, at 12-month follow-up short-term CBT produced significant improvements in binge eating symptoms relative to baseline. Findings suggest that the short-term CBT followed by booster sessions may provide a valuable treatment option for patients with BED.     

The pars triangularis in dyslexia and ADHD: A comprehensive approach

Limited research has been conducted on the structure of the pars triangularis (PT) in dyslexia despite functional neuroimaging research finding it may play a role in phonological processing. Furthermore, research to date has not examined PT size in ADHD even though the right inferior frontal region has been implicated in the disorder. Hence, one of the purposes of this study was to examine the structure of the PT in dyslexia and ADHD. The other purposes included examining the PT in relation to overall expressive language ability and in relation to several specific linguistic functions given language functioning often is affected in both dyslexia and ADHD. Participants included 50 children: 10 with dyslexia, 15 with comorbid dyslexia/ADHD, 15 with ADHD, and 10 controls. Using a 2 (dyslexia or not) × 2 (ADHD or not) MANCOVA, findings revealed PT length and shape were comparable between those with and without dyslexia. However, children with ADHD had smaller right PT lengths than those without ADHD, and right anterior ascending ramus length was related to attention problems in the total sample. In terms of linguistic functioning, presence of an extra sulcus in the left PT was related to poor expressive language ability. In those with adequate expressive language functioning, left PT length was related to phonological awareness, phonological short-term memory and rapid automatic naming (RAN). Right PT length was related to RAN and semantic processing. Further work on PT morphology in relation to ADHD and linguistic functioning is warranted.     

Micro-position effects in visual short term memory

Short-term memory for visually presented eight-digit numbers was tested in a forced recall, read-and-dial task. The digits were presented non-grouped or grouped in 2+2+2+2 or 2+3+3 digit formats. Spatial grouping enhanced memory performance and produced local discontinuities in the serial position curves related to grouping format. These micro-position effects are explained in terms of the relative spatial distinctiveness of individual digits.     

Exploring the forgetting mechanisms in working memory: Evidence from a reasoning span test

In working memory (WM) span tests participants have to maintain to-be-remembered information while processing other, potentially distracting, information. Previous studies have shown that WM span scores are greater when span lists start with a long processing task and end with a short processing task than when these processing tasks are presented in the reverse order (e.g., Towse, Hitch, & Hutton, 2000). In Experiment 1, we obtained a similar stimulus order effect in a reasoning span test, using reasoning sentences that were equated for length in terms of the number of constituent words, but which differed in processing complexity; span scores were greater when lists began with a complex sentence and ended with a simple sentence than when this stimulus order was reversed. In Experiment 2, the stimulus order effect was not found when processing duration was held constant while sentence complexity was varied using a computer-paced moving window presentation paradigm. These results suggest that duration-based constraints can affect degree of forgetting independently of the load generated during processing phases in WM span performance and therefore imply that time-related forgetting can occur in WM span tests, particularly when the difficulty of the processing component blocks active maintenance of to-be-remembered material.     

Redintegration and the benefits of long-term knowledge in verbal short-term memory: an evaluation of Schweickert's (1993) multinomial processing tree model

The impact of four long-term knowledge variables on serial recall accuracy was investigated. Serial recall was tested for high and low frequency words and high and low phonotactic frequency nonwords in 2 groups: monolingual English speakers and French-English bilinguals. For both groups the recall advantage for words over nonwords reflected more fully correct recalls with fewer recall attempts that consisted of fragments of the target memory items (one or two of the three target phonemes recalled correctly); completely incorrect recalls were equivalent for the 2 list types. However, word frequency (for both groups), nonword phonotactic frequency (for the monolingual group), and language familiarity all influenced the proportions of completely incorrect recalls that were made. These results are not consistent with the view that long-term knowledge influences on immediate recall accuracy can be exclusively attributed to a redintegration process of the type specified in multinomial processing tree model of immediate recall. The finding of a differential influence on completely incorrect recalls of these four long-term knowledge variables suggests instead that the beneficial effects of long-term knowledge on short-term recall accuracy are mediated by more than one mechanism.     

Impaired verbal short-term memory in Down syndrome reflects a capacity limitation rather than atypically rapid forgetting

Individuals with Down syndrome suffer from relatively poor verbal short-term memory. Recent work has indicated that this deficit is not caused by problems of audition, speech, or articulatory rehearsal within the phonological loop component of Baddeley and Hitch's working memory model. Given this, two experiments were conducted to investigate whether abnormally rapid decay underlies the deficit. In a first experiment, we attempted to vary the time available for decay using a modified serial recall procedure that had both verbal and visuospatial conditions. No evidence was found to suggest that forgetting is abnormally rapid in phonological memory in Down syndrome, but a selective phonological memory deficit was indicated. A second experiment further investigated possible problems of decay in phonological memory, restricted to item information. The results indicated that individuals with Down syndrome do not show atypically rapid item forgetting from phonological memory but may have a limited-capacity verbal short-term memory system.