On the existence of semantic working memory: evidence for direct semantic maintenance

Despite widespread acknowledgment of the importance of online semantic maintenance, there has been astonishingly little work that clearly establishes this construct. We review the extant work relevant to short-term retention of meaning and show that, although consistent with semantic working memory, most data can be accommodated in other ways. Using a new concurrent probe paradigm, we then report experiments that implicate a semantic maintenance capacity that is independent of phonological or visual maintenance that may build on a mechanism of direct semantic maintenance. Experiments 1 through 5 established that while subjects maintain the meaning of a word, a novel delay-period marker of semantic retention, the semantic relatedness effect, is observed on a concurrent lexical decision task. The semantic relatedness effect refers to slowed response times when subjects make a lexical decision to a probe that is associatively related to the idea they are maintaining, compared to when the probe is unrelated. The semantic relatedness effect occurred for semantic but not for phonological or visual word-form maintenance, dissipated quickly after maintenance ends, and survived concurrent articulatory suppression. The effect disappeared when subjects performed our immediate memory task with a long-term memory strategy rather than with active maintenance. Experiment 6 demonstrated a parallel phonological relatedness effect that occurs for phonological but not semantic maintenance, establishing a full double dissociation between the effects of semantic and phonological maintenance. These findings support a distinct semantic maintenance capacity and provide a behavioral marker through which semantic working memory can be studied.     

Change detection is easier at texture border bars when they are parallel to the border: evidence for V1 mechanisms of bottom-up salience

A vertical bar is salient among horizontal ones by orientation contrast, and, traditionally, bottom up salience is viewed as caused only by feature contrast. Recently, it has been proposed that the primary visual cortex (V1) creates a bottom-up salience map in its outputs, which depends on direct inputs and on contextual inputs by intra-cortical interactions (Li Zhaoping, 2002 Trends in Cognitive Sciences 6 9-16). Since the interactions include iso-feature (eg iso-orientation) suppression, responsible for salience by feature contrast, and collinear facilitation, the V1 proposal predicts that collinear grouping contributes to salience additionally. Accordingly, in orientation textures, texture bars are more salient near texture borders owing to orientation contrast, and are even more salient when they are additionally parallel to the border by collinear grouping. We show that colour changes in texture bars are more detectable when the bars are parallel to the texture border. Since changes are more detectable at salient locations, our finding supports V1 mechanisms for bottom-up salience.     

Direct evidence for a role of working memory in the attentional blink

Theories of selective attention often have a central memory component, which is commonly thought to be limited in some way and is thereby a potential bottleneck in the attentional process. There have been only a few attempts to validate this assertion, and they have produced mixed results. This study presents a specific examination of the link between working memory and attention by engaging active rather than passive memory operations. Two experiments are reported that provide evidence for the involvement of working memory in the attentional blink (AB) phenomenon. Memory loads of increasing size had a detrimental effect on attentional performance within the blink-sensitive interval, but not beyond. Speeded response requirements proved to modulate the AB, but were independent from the memory load effect. Theoretical implications for current models of selective attention are discussed.     

Genetic evidence for multiple biological mechanisms underlying in-group favoritism

In-group favoritism is ubiquitous and associated with intergroup conflict, yet is little understood from a biological perspective. A fundamental question regarding the structure of favoritism is whether it is inflexibly directed toward distinct, "essentialist" categories, such as ethnicity and race, or is deployed in a context-sensitive manner. In this article, we report the first study (to our knowledge) of the genetic and environmental structure of in-group favoritism in the religious, ethnic, and racial domains. We contrasted a model of favoritism based on a single domain-general central affiliation mechanism (CAM) with a model in which each domain was influenced by specific mechanisms. In a series of multivariate analyses, utilizing a large, representative sample of twins, models containing only the CAM or essentialist domains fit the data poorly. The best-fitting model revealed that a biological mechanism facilitates affiliation with arbitrary groups and exists alongside essentialist systems that evolved to process salient cues, such as shared beliefs and ancestry.     

Magnitude estimates for electrical pulses: evidence for two neural mechanisms

The hypothesis that there are two neural mechanisms for electrocutaneous stimulation--one that is sensitive to low current and is adaptive to repeated stimulation and another that is responsive to high current and is less adaptive--was tested in a control and four main experiments. In the main experiments, magnitude estimates obtained for single electrical pulses (of 2-msec duration) were described by a simple power function for each combination of high- and low-current levels and 10 trial blocks. The results were: (1) The slope of the power function for low current was steeper than was that for high current; (2) for low current, the intercept of the power function decreased with increasing block, whereas for high current, it remained constant over blocks; (3) this decrease of the intercept for low current disappeared when judgmental blocks were separated by a rest period of 8 min; (4) the modulus did not affect the slope; (5) for a large modulus combined with low current, the intercept decreased rapidly over trial blocks, whereas for a small modulus combined with high current, the intercept increased over trial blocks. The first four findings support the two-mechanism hypothesis, but the last one may also be interpretable in terms of the regression to absolute scale values.     

Direct democracy and life satisfaction revisited: new evidence for Switzerland

We re-evaluate the relation between cantonal direct democracy and perceived subjective well-being in Switzerland using new data from the Swiss Household Panel. In addition, this study goes beyond previous work by carefully controlling for cultural determinants of happiness such as languages and religion. We find that once language is controlled for, no robust significant relationship between the extent of direct democracy and life satisfaction can be observed. The results also show that direct democracy does not affect well-being within language groups in Switzerland.

Direct reports of motivation for task performance levels: some construct-related evidence

The validity of direct self-reports of motivational force for task performance levels was examined in three studies. Such measures have been used as true-scorelike criteria for computed measures of force and have advantages as measures in their own right. Results suggested that simple, direct self-reports should be useful in some research settings, but their validity as assessments of motivational force per se may be influenced by both wording and context.     

Specialised higher-level mechanisms for facial-symmetry perception: evidence from orientation-tuning functions

Bilateral symmetry is important in many perceptual analyses from low-level figure-ground segmentation to higher-level face and object perception. Despite the success of low-level, image-based symmetry-detection models, these may not provide a complete account of symmetry perception. Better symmetry detection and stronger preferences for symmetry in upright faces than comparable patterns (e.g. inverted faces) that do not engage specialised face-coding mechanisms suggest a contribution of higher-level mechanisms to symmetry perception. We replicated better symmetry detection and stronger symmetry preferences for upright than inverted faces in experiment 1, and examined their orientation tuning in more detail in experiment 2. Decreasing performance as faces are mis-oriented away from the canonical upright orientation is the signature of specialised face-processing mechanisms, which are engaged less effectively as faces are mis-oriented. Lower-level symmetry-detection mechanisms, which operate better with vertical than horizontal, and horizontal than oblique, axes of symmetry would produce a W-shaped orientation-tuning function. Identical orientation-tuning functions were obtained for symmetry detection and preferences. Both declined with increasing mis-orientation over the 0 degrees-135 degrees range, consistent with a contribution from specialised face-coding mechanisms. Both increased from 135 degrees to 180 degrees, consistent with reliance on lower-level image-based mechanisms for severely misoriented faces. Taken together, the results implicate specialised, higher-level mechanisms in the detection of, and preference for, facial symmetry.     

Priming visual face-processing mechanisms: electrophysiological evidence

Accumulated evidence from electrophysiology and neuroimaging suggests that face perception involves extrastriate visual mechanisms specialized in processing physiognomic features and building a perceptual representation that is categorically distinct and can be identified by face-recognition units. In the present experiment, we recorded event-related brain potentials in order to explore possible contextual influences on the activity of this perceptual mechanism. Subjects were first exposed to pairs of small shapes, which did not elicit any face-specific brain activity. The same stimuli, however, elicited face-specific brain activity after subjects saw them embedded in schematic faces, which probably primed the subjects to interpret the shapes as schematic eyes. No face-specific activity was observed when objects rather than faces were used to form the context. We conclude that the activity of face-specific extrastriate perceptual mechanisms can be modulated by contextual constraints that determine the significance of the visual input.     

Scene-based and object-centered inhibition of return: evidence for dual orienting mechanisms

We investigated whether inhibition of return (IOR) could be observed in location-based, scene-based, and object-centered frames of reference. IOR was found to move both with a separate cued object (scene-based) and with a location within a single rotating object (object-centered). Importantly, however, IOR was also associated with the environmental location cued when cuing was of a separate object (scene-based), whereas facilitation of the cued location was found when cuing was of a component within an object. These results suggest that location is of central importance to scene-based representations of separate objects, which appear to be encoded in viewer-centered coordinates, whereas environmental locus is of little relevance when attention orients within a single object. The results also provide further evidence for the coexistence of both excitation and inhibition associated with uninformative exogenous cues.     

Dynamic aspects of stimulus-response correspondence: evidence for two mechanisms involved in the Simon effect

It has been recently proposed that the time course of the Simon effect may vary across tasks, which might reflect different types of stimulus-response (S-R) transmissions (E. Wascher, U. Schatz, T. Kuder, & R. Verleger, 2001). The authors tested this notion in 4 experiments by comparing Simon effects evoked by horizontal and vertical S-R arrangements. The temporal properties of the effect, as well as lateralized readiness potential-difference waves, indicated a fast and transient influence of the horizontal, but a slow and sustained influence of the vertical spatial stimulus feature on performance. Additional evidence for this temporal dissociation was obtained in experiments that induced a shortening or lengthening of the mean response time. Thus, the data strongly indicate that there are 2 temporally dissociable mechanisms involved in generating the Simon effect for horizontal and vertical S-R relations.     

On the existence of independent explicit and implicit learning systems: An examination of some evidence

Hayes and Broadbent (1988), among others, have proposed that there are two independent systems of learning in humans. In their theory, they postulate that theexplicit learning system gives rise to knowledge that is verbally describable, whereas theimplicit learning system deals with knowledge that is not amenable to verbal report. Hayes and Broadbent presented data that they claimed supports a distinction between these two systems of learning. Their experiments involved the performance of subjects on two superficially similar tasks, and their claim was that one of the tasks induced learning in the explicit system, and the other induced learning in the implicit system. However, in five experiments here, we failed to find any convincing support for their empirical or theoretical claims. Our results suggest that the two tasks do not differ by inducing different types of learning, but simply differ in their degree of difficulty.     

Family interventions in schizophrenia: evidence for efficacy and proposed mechanisms of change

Family intervention for psychosis developed from empirical work on the role of emotion in families of those caring for someone with schizophrenia. The level of expressed emotion (EE) has been shown to be a robust predictor of subsequent outcome for service users returning to live in family settings. There is also evidence that staff have similar attitudes. This has led to the development of specific family interventions for schizophrenia. NICE Guidelines for Schizophrenia (2003) confirm that family intervention is effective at reducing service user relapse rates and recommends it for those in contact with carers. Exactly how family intervention improves outcome is less clear. A recent model of psychosis proposes a primarily emotional rather than cognitive route for family factors, and some evidence is presented which supports this. Implications for family interventions are discussed.     

Imitation: definitions, evidence, and mechanisms

Imitation can be defined as the copying of behavior. To a biologist, interest in imitation is focused on its adaptive value for the survival of the organism, but to a psychologist, the mechanisms responsible for imitation are the most interesting. For psychologists, the most important cases of imitation are those that involve demonstrated behavior that the imitator cannot see when it performs the behavior (e.g., scratching one's head). Such examples of imitation are sometimes referred to as opaque imitation because they are difficult to account for without positing cognitive mechanisms, such as perspective taking, that most animals have not been acknowledged to have. The present review first identifies various forms of social influence and social learning that do not qualify as opaque imitation, including species-typical mechanisms (e.g., mimicry and contagion), motivational mechanisms (e.g., social facilitation, incentive motivation, transfer of fear), attentional mechanisms (e.g., local enhancement, stimulus enhancement), imprinting, following, observational conditioning, and learning how the environment works (affordance learning). It then presents evidence for different forms of opaque imitation in animals, and identifies characteristics of human imitation that have been proposed to distinguish it from animal imitation. Finally, it examines the role played in opaque imitation by demonstrator reinforcement and observer motivation. Although accounts of imitation have been proposed that vary in their level of analysis from neural to cognitive, at present no theory of imitation appears to be adequate to account for the varied results that have been found.     

Memory mechanisms in pigeons: evidence of base-rate neglect

In delayed matching to sample, once acquired, pigeons presumably choose comparisons according to their memory for (the strength of) the sample. When memory for the sample is sufficiently weak, comparison choice should depend on the history of reinforcement associated with each of the comparison stimuli. In the present research, pigeons acquired two matching tasks in which Sample S1 was associated with one comparison from each task, C1 and C3, whereas Sample S2 was associated with Comparison C2, and Sample S3 was associated with Comparison C4. As the retention interval increased, the pigeons showed a bias to choose the comparison (C1 or C3) associated with the more frequently occurring sample (S1). Thus, pigeons were sensitive also to the (irrelevant) likelihood that each of the samples was presented. The results suggest that pigeons may allow their reference memory for the overall sample frequency to influence comparison choice, independent of the comparison stimuli present.     

Independence of speed and accuracy in visual search: evidence for separate mechanisms.

Data from two studies that tested children's attention using visual search for a series of targets in a complex display and a sustained-attention task waiting for signals in a similar display were subjected to Factor Analysis to explore previous indications that speed and accuracy (the number of false alarms to nontargets) on this task reflect different mechanisms. The two factors identified confirmed the separation of these two measures and also suggested that the speed factor was related to Mental Age, while the accuracy factor was related to ratings of attentional ability. It is suggested that ratings of attentional ability reflect the efficiency of executive functions, displayed in the ability to inhibit responses to nontargets in these tasks, while speed of search is related to processing speed in the nervous system. Therefore intelligence and attentional ability depend on different underlying features of the nervous system.