The Individuality of Species: Some Reflections on the Debate

The thesis that species are individuals, and not classes as the traditional view had it, has been influential in the last 25 years. In this paper David Hull's arguments for the thesis are surveyed, as well as some counterarguments presented by Philip Kitcher. It is claimed that though species can be conceptualized as individuals, we are not compelled to view them in that way. The importance of the issue seems to have been somewhat exaggerated. However, it might happen that empirical findings concerning species selection would strengthen the case for the thesis, thereby rendering it straightforwardly empirical. The applicability of teleological explanation is suggested as a criterion for biological individuality. This revised version was published online in June 2006 with corrections to the Cover Date.     

Perceived tempo change is dependent on base tempo and direction of change: Evidence for a generalized version of Schulze's (1978) internal beat model

Assumptions of a theory, still influential, of tempo perception by Schulze (1978) are reconsidered in view of counter-evidence from other time-perception and timing studies. Specifically, it is shown that the role of base tempo of stimuli and the orientation of tempo change (acceleration versus deceleration) have to be incorporated in them. Therefore, Schulze's assumptions were extended so as to include the two stimulus parameters. A generalized version of Schulze's internal beat model, one of three formal elaborations of the theory, was tested in an experiment which required subjects (N = 17) to tell the direction of change (acceleration or deceleration) in metronomic tone sequences presented at tempi of 1, 2, or 4 Hz, the amount of tempo change being varied in steps of 2% between –10% (acceleration) and + 10%, including zero change. Psychometric curves obtained from logistic regression analysis showed the limitation of the original assumptions and supported the proposed generalization of Schulze's model. The validity of the theoretical interpretation of the data was discussed with respect to some methodological constraints in the experiment, such as the presentation of the different tempo conditions and the time length of the metronomic stimuli used, and with respect to their applicability to the performance of expressive drift (rubato versus accelerando) in music.     

Development of strategies for recalling letter sequences

Kindergarten, second-grade, and fourth-grade children (6, 8, and 10 years of age, respectively) were asked to recall letter sequences on a task that required the use of: (a) a verbal strategy; (b) a positional strategy; or (c) either strategy. Additional trials, allowing either strategy, were interspersed among those requiring a verbal or positional strategy; strategy use was determined from performance on these interspersed trials. The results show that children at all grade levels attempted to use a task-appropriate strategy. Performance on the verbal task showed a more marked developmental increase than did performance on the positional task. A second experiment replicated the first with the interspersed trials removed. A third experiment was designed to determine whether letter names interfered with older children's efficient use of a positional strategy. Even with this source of interference removed, the developmental pattern of Experiments 1 and 2 was replicated. There was a Sex by Condition interaction in Experiments 2 and 3 which showed that males do better in the condition requiring a positional strategy, and females do better in the condition requiring a verbal strategy.     

Investigating the Appraisal Patterns of Regret and Disappointment

Regret and disappointment are the two emotions that are most closely linked to decision making. This study compares the appraisal patterns of the two emotions. This is done in the context of the related negative emotions anger and sadness. The results show clear differences between regret and disappointment in this respect while replicating prior findings concerning the appraisal patterns of anger and sadness. The results are of interest for emotion researchers and decision researchers.     

Two-month-old infants of depressed mothers show mild, delayed and persistent change in emotional state after non-contingent interaction

The aim of this study was to explore how early infants show different responses to non-contingent maternal behavior according to their past history of relations with their mother. Two groups of 2-month-olds interacted with their mother who was assessed as depressed (group 1) or non-depressed (group 2). Although they received a continuous image and voice of their mothers, the infants were presented either a 30-s contingent maternal communication (live episode 1) or a thirty second non-contingent episode (replay of prior maternal communication), or again a 30-s contingent live episode (live2). The lower percentage of negative facial expressions displayed during replay by infants of depressed mothers suggests on one hand that they are less sensitive to a non-contingent maternal behavior than infants of non-depressed mothers. However, within group comparisons demonstrate a notable difference: while infants of non-depressed mothers show a U curve of smile, infants of depressed mothers show decreasing smile throughout the three episodes. Taken together, these results plead in favour of an other profile of sensitivity displayed by infants of depressed mothers. Instead of the strong but short-term reaction of infants of non-depressed mothers, the response of infants of depressed mothers appeared to be a mild, delayed and more persistent change in emotional state. These findings are discussed in the light of possible cognitive and social incidence of passive avoidance of stressful events in infants of depressed mothers.     

Social reactions to adult crying: the help-soliciting function of tears

The authors investigated how people believe they respond to crying individuals. Participants (N = 530) read 6 vignettes describing situations in which they encountered a person who either cried or did not cry. Participants reported they would give more emotional support to and express less negative affect toward a crying person than a noncrying person. However, regression analyses revealed that participants judged a crying person less positively than a noncrying person and felt more negative feelings in the presence of a crying person than a noncrying person. The valence of the situation strongly moderated these reactions. Overall, results support the theory that crying is an attachment behavior designed to elicit help from others.     

Mokken Scale Analysis for Dichotomous Items Using Marginal Models

Scalability coefficients play an important role in Mokken scale analysis. For a set of items, scalability coefficients have been defined for each pair of items, for each individual item, and for the entire scale. Hypothesis testing with respect to these scalability coefficients has not been fully developed. This study introduces marginal modelling as a framework to derive the standard errors for the scaling coefficients and test hypotheses about these coefficients. Several examples demonstrate the possibilities of marginal modelling in Mokken scale analysis. These possibilities include testing whether Mokken’s criteria for a scale are satisfied, testing whether scalability coefficients of different items are equal, and testing whether scalability coefficients are equal across different groups.     

I see what you mean: theta power increases are involved in the retrieval of lexical semantic information

An influential hypothesis regarding the neural basis of the mental lexicon is that semantic representations are neurally implemented as distributed networks carrying sensory, motor and/or more abstract functional information. This work investigates whether the semantic properties of words partly determine the topography of such networks. Subjects performed a visual lexical decision task while their EEG was recorded. We compared the EEG responses to nouns with either visual semantic properties (VIS, referring to colors and shapes) or with auditory semantic properties (AUD, referring to sounds). A time-frequency analysis of the EEG revealed power increases in the theta (4-7Hz) and lower-beta (13-18Hz) frequency bands, and an early power increase and subsequent decrease for the alpha (8-12Hz) band. In the theta band we observed a double dissociation: temporal electrodes showed larger theta power increases in the AUD condition, while occipital leads showed larger theta responses in the VIS condition. The results support the notion that semantic representations are stored in functional networks with a topography that reflects the semantic properties of the stored items, and provide further evidence that oscillatory brain dynamics in the theta frequency range are functionally related to the retrieval of lexical semantic information.     

Hippocampal low-frequency stimulation and chronic mild stress similarly disrupt fear extinction memory in rats

Disruptions of fear extinction-related potentiation of synaptic efficacy in the connection between the hippocampus (HPC) and the medial prefrontal cortex (mPFC) have been shown to impair the recall of extinction memory. This study was undertaken to examine if chronic mild stress (CMS), which is known to alter induction of HPC–mPFC long-term potentiation, would also interfere with both extinction-related HPC–mPFC potentiation and extinction memory. Following fear conditioning (5 tone-shock pairings), rats were submitted to fear extinction (20 tone-alone presentations), which produced an increase in the amplitude of HPC–mPFC field potentials. HPC low-frequency stimulation (LFS), applied immediately after training, suppressed these changes and induced fear return during the retention test (5 tone-alone presentations). CMS, delivered before fear conditioning, did not interfere with fear extinction but blocked the development of extinction-related potentiation in the HPC–mPFC pathway and impaired the recall of extinction. These findings suggest that HPC LFS may provoke metaplastic changes in HPC outputs that may mimic alterations associated with a history of chronic stress.