The hippocampus and prefrontal cortex are differentially involved in serial memory retrieval in non-stress and stress conditions

We previously showed that 24 h after learning, mice significantly remembered the first (D1) but not the second (D2) discrimination in a serial spatial task and that an acute stress delivered 5 min before the test phase reversed this memory retrieval pattern.A first experiment evaluated the effects of dorsal hippocampus (HPC) or prefrontal cortex (PFC) lesions, these two brain areas being well-known for their involvement in serial and spatial memory processes. For this purpose, six independent groups of mice were used: non-lesioned (controls), PFC or HPC-lesioned animals, submitted or not to an acute stress (electric footshocks; 0.9 mA). Results show that (i) non-stressed controls as well as PFC-lesioned mice (stressed or not) remembered D1 but not D2; (ii) stressed controls and HPC-lesioned mice (stressed or not) remembered D2 but not D1; (iii) stress significantly increased plasma corticosterone in controls and PFC-lesioned mice, but not in HPC-lesioned mice which already showed a significant plasma corticosterone increase in non-stressed condition.Since data from this first experiment showed that stress inhibited the hippocampal-dependent D1 memory retrieval, a second experiment evaluated the behavioral effect of intrahippocampal corticosterone injection in non-stressed mice. Results show that intrahippocampal corticosterone injection induced a reversal of serial memory retrieval pattern similar to that induced by acute stress.Overall, our study shows that (i) in non-stress condition, the emergence of D1 is HPC-dependent; (ii) in stress condition, the emergence of D2 requires the PFC integrity; moreover, intrahippocampal corticosterone injection mimicked the effects of stress in the CSD task.     

Does making a conversation asynchronous reduce the negative impact of phone call on driving?

Mobile phone use at the wheel has a proven negative impact on driving. This paper aims to assess whether using an answerphone instead of a normal phone reduces this negative impact. The answerphone makes communication asynchronous and splits it into three disconnected and successive phases: interaction with the voice interface, listening to the message and answering, which have been evaluated separately.The experiment was conducted on a fixed base simulator, with 30 participants (half male and female, aged from 18 to 50 years, driving at least 5000 km per year).The results show better scores for correct responses to stimuli for answerphone communications than for phone communications, although response times were higher in both communication conditions than in the driving alone condition. When the three phases of answerphone use were compared, interacting with the answerphone and listening to the message were found to be significantly less disturbing than answering, in terms of correct responses and response times.By making the conversation asynchronous, the answerphone avoids direct interaction between driver and caller. The fact that communication is under the driver’s control allows him/her to pace the interaction better. Lastly, splitting up the conversation into different phases decreases the overall task difficulty.     

The Sound of Mute Vowels in Auditory Word-Stem Completion

Some studies have argued that orthography can influence speakers when they perform oral language tasks. Words containing a mute vowel provide well-suited stimuli to investigate this phenomenon because mute vowels, such as the second <e> in <vegetable>, are present orthographically but absent phonetically. Using an auditory word-stem completion task, we tested whether subjects were influenced by the presence of mute vowels. We ran experiments in two languages which contain numerous mute-vowel words: Tigrinya, which uses a syllabic/moraic writing system, and French, which uses an alphabetic writing system. We argue that Tigrinya and French speakers based their completion on the sound form of words, rather than the written one. We suggest that the presence of mute vowels at the underlying phonological level, rather than their orthographic representation, influences speakers in the word-stem completion task. Some effects previously attributed to orthography may instead be attributable to underlying phonological representations.     

Expectancies for social contingency in 2-month-olds

In a classic report, Murray and Trevarthen (Emotional regulation of interaction between two-month-olds and their mothers. In T. Field & N. Fox (Eds), Social perception in infants (pp. 101–125). Norwood, NJ: Ablex, 1985) suggested that 6- to 12-week-olds were sensitive to contingency in maternal stimulation because they became upset during the replay of their mothers’ behavior during an initial period of live interaction over closed circuit TV. However, a number of concerns were raised about the procedure and it was argued that infants may simply have become increasingly fussy over time. To clarify this very important issue, we adopted a three-condition design (live–replay–live) and modified Murray and Trevarthen’s procedure by inserting a seamless shift from the initially live interaction period to a replay period of good maternal behavior. This was followed by a seamless shift back to a subsequent live interaction. Two-month-old smiling and gaze decreased while frowning and mouth closures increased during the replay period relative to the initial live interaction period, replicating Murray and Trevarthen’s results. Fussiness over time did not account for these results because seven of the ten babies increased their positive behaviors and decreased negative behaviors during the second live interaction period, and there was a significant increase in their visual attention to their mothers, thus suggesting a renewed interest in the previously noncontingent partner.     

Why Do People Fail to Adopt Environmental Protective Behaviors? Toward a Taxonomy of Environmental Amotivation1

Individuals' reasons for their lack of motivation toward environmental protective behaviors were proposed: amotivation because of strategy, capacity, effort, and helplessness beliefs. Confirmatory factor analyses and correlations between the four types of amotivation and constructs related to the environment supported the validity of the constructs. A structural model in which helplessness beliefs could be predicted by the other sets of beliefs, and wherein strategy and ability beliefs resulted from effort beliefs, was tested. All estimated parameters were significant, with the exception of one link: amotivation because of effort beliefs did not display a significant relationship with helplessness beliefs. The importance of understanding why individuals may be amotivated and the strategies liable to help reduce their lack of motivation are discussed.     

Phonetic recoding and reading difficulty in beginning readers

The results of a recent study (Liberman, Shankweiler, Liberman, Fowler, & Fischer, 1977) suggest that good beginning readers are more affected than poor readers by the phonetic characteristics of visually presented items in a recall task. The good readers made significantly more recall errors on strings of letters with rhyming letter names than on nonrhyming sequences; in contrast, the poor readers made roughly equal numbers of errors on the rhyming and nonrhyming letter strings. The purpose of the present study was to determine whether the interaction between reading ability and phonetic similarity is solely determined by different rehearsal strategies of the two groups. Accordingly, good and poor readers were tested on rhyming and nonrhyming words using a recognition memory paradigm that minimized the opportunity for rehearsal. Performance of the good readers was more affected by phonetic similarity than that of the poor readers, in agreement with the earlier study. The present findings support the hypothesis that good and poor readers do differ in their ability to access a phonetic representation.     

Consumption and community: choices for women over forty

• Women in their 40s face a range of issues regarding how they choose to present themselves to the world; often these choices involve forms of consumption. We talked to two groups of British women and discussed how they felt about themselves and the pressures upon them. We present a discussion which aims to synthesize some of the key features of how these women face their futures and suggest potential theoretical positions to help encapsulate women's present and future selves. We suggest that there are a number of pressures that may engender alternative consumption choices and these are often set within a wider sense of female community. The concept of community should prove useful for further theorising on women's future consumption choices.

Copyright © 2006 John Wiley & Sons, Ltd.     

Frequency-range discriminations and absolute pitch in black-capped chickadees (Poecile atricapillus), mountain chickadees (Poecile gambeli), and zebra finches (Taeniopygia guttata)

The acoustic frequency ranges in birdsongs provide important absolute pitch cues for the recognition of conspecifics. Black-capped chickadees (Poecile atricapillus), mountain chickadees (Poecile gambeli), and zebra finches (Taeniopygia guttata) were trained to sort tones contiguous in frequency into 8 ranges on the basis of associations between response to the tones in each range and reward. All 3 species acquired accurate frequency-range discriminations, but zebra finches acquired the discrimination in fewer trials and to a higher standard than black-capped or mountain chickadees, which did not differ appreciably in the discrimination. Chickadees' relatively poorer accuracy was traced to poorer discrimination of tones in the higher frequency ranges. During transfer tests, the discrimination generalized to novel tones when the training tones were included, but not when they were omitted.     

The nature of music from a biological perspective

Music, as language, is a universal human trait. Throughout human history and across all cultures, people have produced and enjoyed music. Despite its ubiquity, the musical capacity is rarely studied as a biological function. Music is typically viewed as a cultural invention. In this paper, the evidence bearing on the biological perspective of the musical capacity is reviewed. Related issues, such as domain-specificity, innateness, and brain localization, are addressed in an attempt to offer a unified conceptual basis for the study of music processing. This scheme should facilitate the study of the biological foundations of music by bringing together the fields of genetics, developmental and comparative research, neurosciences, and musicology.     

Optic-flow-based perception of two-dimensional trajectories and the effects of a single landmark

Human observers can detect their heading direction on a short time scale on the basis of optic flow. We investigated the visual perception and reconstruction of visually travelled two-dimensional (2-D) trajectories from optic flow, with and without a landmark. As in our previous study, seated, stationary subjects wore a head-mounted display in which optic-flow stimuli were shown that simulated various manoeuvres: linear or curvilinear 2-D trajectories over a horizontal plane, with observer orientation either fixed in space, fixed relative to the path, or changing relative to both. Afterwards, they reproduced the perceived manoeuvre with a model vehicle, whose position and orientation were recorded. Previous results had suggested that our stimuli can induce illusory percepts when translation and yaw are unyoked. We tested that hypothesis and investigated how perception of the travelled trajectory depends on the amount of yaw and the average path-relative orientation. Using a structured visual environment instead of only dots, or making available additional extra-retinal information, can improve perception of ambiguous optic-flow stimuli. We investigated the amount of necessary structuring, specifically the effect of additional visual and/or extra-retinal information provided by a single landmark in conditions where illusory percepts occur. While yaw was perceived correctly, the travelled path was less accurately perceived, but still adequately when the simulated orientation was fixed in space or relative to the trajectory. When the amount of yaw was not equal to the rotation of the path, or in the opposite direction, subjects still perceived orientation as fixed relative to the trajectory. This caused trajectory misperception because yaw was wrongly attributed to a rotation of the path: path perception is governed by the amount of yaw in the manoeuvre. Trajectory misperception also occurs when orientation is fixed relative to a curvilinear path, but not tangential to it. A single landmark could improve perception. Our results confirm and extend previous findings that, for unambiguous perception of ego-motion from optic flow, additional information is required in many cases, which can take the form of fairly minimal, visual information.