People categorize objects slowly when visual input is highly impoverished instead of optimal. While bottom-up models may explain a decision with optimal input, perceptual hypothesis testing (PHT) theories implicate top-down processes with impoverished input. Brain mechanisms and the time course of PHT are largely unknown. This event-related potential study used a neuroimaging paradigm that implicated prefrontal cortex in top-down modulation of occipitotemporal cortex. Subjects categorized more impoverished and less impoverished real and pseudo objects. PHT theories predict larger (...) impoverishment effects for real than pseudo objects because top-down processes modulate knowledge only for real objects, but different PHT variants predict different timing. Consistent with parietal-prefrontal PHT variants, around 250 ms, the earliest impoverished real object interaction started on an N3 complex, which reflects interactive cortical activity for object cognition. N3 impoverishment effects localized to both prefrontal and occipitotemporal cortex for real objects only. The N3 also showed knowledge effects by 230 ms that localized to occipitotemporal cortex. Later effects reflected (a) word meaning in temporal cortex during the N400, (b) internal evaluation of prior decision and memory processes and secondary higher-order memory involving anterotemporal parts of a default mode network during posterior positivity (P600), and (c) response related activity in posterior cingulate during an anterior slow wave (SW) after 700 ms. Finally, response activity in supplementary motor area during a posterior SW after 900 ms showed impoverishment effects that correlated with RTs. Convergent evidence from studies of vision, memory, and mental imagery which reflects purely top-down inputs, indicates that the N3 reflects the critical top-down processes of PHT. A hybrid multiple-state interactive, PHT and decision theory best explains the visual constancy of object cognition. (shrink)

We argue that the pivotal role assigned by Northoff to the principle of top-down modulation in catatonia might successfully be applied to other symptoms of schizophrenia, for example, hallucinations. Second, we propose that Northoff's account would benefit from a more comprehensive analysis of the cognitive level of explanation. Finally, contrary to Northoff, we hypothesize that “top-down modulation” might play as important a role as “horizontal modulation” in affective-behavioral alterations.

Behrendt & Young's (B&Y's) theory offers a potentially important perspective on the neurobiology of schizophrenia, but it remains incomplete. In addition to bottom-up contributions, such as those associated with disturbances in sensory constraints on cognitive processes, a comprehensive model requires the integration of the consequences of abnormal top-down modulation of input processing for the evolution of “underconstrained” perceptions. Dysfunctional cholinergic modulation of input functions represents a necessary mechanism for the generation of false perceptions.

Differential diagnosis of motor symptoms, for example, akinesia, may be difficult in clinical neuropsychiatry. Symptoms may be either of neurologic origin, for example, Parkinson's disease, or of psychiatric origin, for example, catatonia, leading to a so-called “conflict of paradigms.” Despite their different origins, symptoms may appear more or less clinically similar. Possibility of dissociation between origin and clinical appearance may reflect functional brain organisation in general, and cortical-cortical/subcortical relations in particular. It is therefore hypothesized that similarities and differences between Parkinson's (...) disease and catatonia may be accounted for by distinct kinds of modulation between cortico-cortical and cortico-subcortical relations. Catatonia can be characterized by concurrent motor, emotional, and behavioural symptoms. The different symptoms may be accounted for by dysfunction in orbitofrontal-prefrontal/parietal cortical connectivity reflecting “horizontal modulation” of cortico-cortical relation. Furthermore, alteration in “top-down modulation” reflecting “vertical modulation” of caudate and other basal ganglia by GABA-ergic mediated orbitofrontal cortical deficits may account for motor symptoms in catatonia. Parkinson's disease, in contrast, can be characterized by predominant motor symptoms. Motor symptoms may be accounted for by altered “bottom-up modulation” between dopaminergic mediated deficits in striatum and premotor/motor cortex. Clinical similarities between Parkinson's disease and catatonia with respect to akinesia may be related with involvement of the basal ganglia in both disorders. Clinical differences with respect to emotional and behavioural symptoms may be related with involvement of different cortical areas, that is, orbitofrontal/parietal and premotor/motor cortex implying distinct kinds of modulation – “vertical” and “horizontal” modulation, respectively. Key Words: Bottom-up modulation; catatonia; horizontal modulation; Parkinson's disease; top-down modulation; vertical modulation. (shrink)

Selective attention depends on goal-directed and stimulus-driven modulatory factors, each relayed by different brain rhythms. Under certain circumstances, stress-related states can change the balance between goal-directed and stimulus-driven factors. However, the neuronal mechanisms underlying these changes remain unclear. In this study, we explored how psychosocial stress can modulate brain rhythms during an attentional task and a task-free period. We recorded the EEG and ECG activity of 42 healthy participants subjected to either the Trier Social Stress Test, a controlled procedure to (...) induce stress, or a comparable control protocol, flanked by an attentional task, a 90 s of task-free period and a state of anxiety questionnaire. We observed that psychosocial stress induced an increase in heart rate, self-reported anxiety, and alpha power synchronization. Also, psychosocial stress evoked a relative beta power increase during correct trials of the attentional task, which correlates positively with anxiety and heart rate increase, and inversely with attentional accuracy. These results suggest that psychosocial stress affects performance by redirecting attentional resources toward internal threat-related thoughts. An increment of endogenous top-down modulation reflected an increased beta-band activity that may serve as a compensatory mechanism to redirect attentional resources toward the ongoing task. The data obtained here may contribute to designing new ways of clinical management of the human stress response in the future and could help to minimize the damaging effects of persistent stressful experiences. (shrink)

Catatonia resulting from a general medical condition (as defined in the DSM-IV) seems to account for a large percentage of patients presenting with catatonia in psychiatric settings. In view of Dr. Northoff's hypothesis, it is important to emphasize that medical catatonias provide additional information to support his neuropsychiatric hypothesis of the anatomical and biochemical mechanisms of catatonia.

In many fields in the life sciences investigators refer to downward or top-down causal effects. Craver and Bechtel defended the view that such cases should be understood in terms of a constitution relation between levels in a mechanism and causation as solely an intra-level relation. Craver and Bechtel, however, provided insufficient specification as to when entities constitute a higher-level mechanism. In this paper I appeal to graph-theoretic representations of networks that are now widely employed in systems biology and neuroscience (...) to identify mechanisms with the modules that exhibit high clustering. As a result of the interconnections of nodes in these modules/mechanisms, they often exhibit complex dynamic behaviors that constrain how the individual components respond to external inputs, an important feature of cases viewed as involving top-down causation. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 11.1 (2004) 65-70 [Access article in PDF] Top-Down and Bottom-Up in Delusion Formation Jakob Hohwy Keywords delusions, top-down, bottom-up, predictive coding Some delusions may arise as responses to unusual experiences (Davies et al. 2001; Maher 1974;). The implication is that delusion formation in some cases involves some kind of bottom-up mechanism—roughly, from perception to belief. Delusion formation may also involve some kind of (...) top-down mechanism. This could be in the shape of a patient's flawed background beliefs, or biases, which somehow modulate perception or ensure delusional interpretations of experience. There is little agreement about what kind of mechanism is primary in delusion formation, or, indeed, what the particular mechanisms and their neural substrates might be.In the evaluation of top-down and bottom-up mechanisms in delusion formation, a number of conceptual questions should be addressed (Davies and Coltheart 2000). For example, if there is an experiential component, why is a hypothesis with a delusional explanation of the unusual experience seen as relevant? Why do the subjects come to believe it tenaciously? How come some unusual experiences do not develop into delusions?A number of empirical findings also need to be taken into account: for example, the damage to the autonomic system in Capgras delusion (Ellis et al. 1997), the decreased ability for fast error correction in schizophrenia (Frith and Done 1989), modulation of activity in parietal cortex in delusions of alien control and other passivity experiences (Blakemore, Oakley, and Frith 2003), and also in schizophrenia, the increased sensitivity to self-produced stimuli, such as tickling oneself (Blakemore et al. 2000) and the sound of one's own voice (Ford et al. 2001).Theory choice can also be guided by philosophical doctrines about, for example, the nature of belief, the constitutive role of rationality, and intersubjectivity and the nature of judgements about the external world. It is natural, however, to let beliefs about philosophical doctrine be secondary to empirical findings and conceptual issues.The distinction between bottom-up and top-down mechanisms is particularly sharp in John Campbell's (2001) account of delusions and in Tim Bayne and Elisabeth Pacherie's (2004) discussion of Campbell. In this discussion, top-down approaches are associated with the general philosophical doctrine of rationalism, and bottom-up approaches with the philosophical doctrine of empiricism. Campbell's account is top-down because he posits delusional framework beliefs that arise directly as a result of brain damage or malfunction, and that work in some top-down fashion on the interpretation of experience. Bayne [End Page 65] and Pacherie convincingly defend empiricism against Campbell's rationalist account. Among their many other objections, they briefly puzzle about how a delusional framework belief (e.g., that one's spouse is an impostor) in a top-down fashion could cause the damage to the autonomic system seen in the Capgras and Cotard delusions (2004, 1). I think this is a very important objection because skin conductance data are part of the evidence for the bottom-up hypothesis concerning the Capgras delusion. We could add to this, for example, that it is mysterious how belief in a top-down fashion could cause people with schizophrenia to be worse at fast error correction than normal controls, to be better at tickling themselves than normal controls, and to have an increased response to the sound of their own voice.On the other hand, although the skin conductance response (SCR) evidence suggests a bottom-up approach to the Capgras delusion, it does not explain the character of the subjective experience that is hypothesized to give rise to the delusional belief: reduced SCR is not part of the experience itself (thanks to Ian Gold for discussion of this). Something more is required to give a full account of the type of experience that gives rise to the delusion. Further, as they stand, most bottom-up accounts are unable to account for why reality testing fails for beliefs based on these experiences.Neither rationalism nor empiricism on their own seem able to address the conceptual questions while paying... (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 11.1 (2004) 65-70 [Access article in PDF] Top-Down and Bottom-Up in Delusion Formation Jakob Hohwy Keywords delusions, top-down, bottom-up, predictive coding Some delusions may arise as responses to unusual experiences (Davies et al. 2001; Maher 1974;). The implication is that delusion formation in some cases involves some kind of bottom-up mechanism—roughly, from perception to belief. Delusion formation may also involve some kind of (...) top-down mechanism. This could be in the shape of a patient's flawed background beliefs, or biases, which somehow modulate perception or ensure delusional interpretations of experience. There is little agreement about what kind of mechanism is primary in delusion formation, or, indeed, what the particular mechanisms and their neural substrates might be.In the evaluation of top-down and bottom-up mechanisms in delusion formation, a number of conceptual questions should be addressed (Davies and Coltheart 2000). For example, if there is an experiential component, why is a hypothesis with a delusional explanation of the unusual experience seen as relevant? Why do the subjects come to believe it tenaciously? How come some unusual experiences do not develop into delusions?A number of empirical findings also need to be taken into account: for example, the damage to the autonomic system in Capgras delusion (Ellis et al. 1997), the decreased ability for fast error correction in schizophrenia (Frith and Done 1989), modulation of activity in parietal cortex in delusions of alien control and other passivity experiences (Blakemore, Oakley, and Frith 2003), and also in schizophrenia, the increased sensitivity to self-produced stimuli, such as tickling oneself (Blakemore et al. 2000) and the sound of one's own voice (Ford et al. 2001).Theory choice can also be guided by philosophical doctrines about, for example, the nature of belief, the constitutive role of rationality, and intersubjectivity and the nature of judgements about the external world. It is natural, however, to let beliefs about philosophical doctrine be secondary to empirical findings and conceptual issues.The distinction between bottom-up and top-down mechanisms is particularly sharp in John Campbell's (2001) account of delusions and in Tim Bayne and Elisabeth Pacherie's (2004) discussion of Campbell. In this discussion, top-down approaches are associated with the general philosophical doctrine of rationalism, and bottom-up approaches with the philosophical doctrine of empiricism. Campbell's account is top-down because he posits delusional framework beliefs that arise directly as a result of brain damage or malfunction, and that work in some top-down fashion on the interpretation of experience. Bayne [End Page 65] and Pacherie convincingly defend empiricism against Campbell's rationalist account. Among their many other objections, they briefly puzzle about how a delusional framework belief (e.g., that one's spouse is an impostor) in a top-down fashion could cause the damage to the autonomic system seen in the Capgras and Cotard delusions (2004, 1). I think this is a very important objection because skin conductance data are part of the evidence for the bottom-up hypothesis concerning the Capgras delusion. We could add to this, for example, that it is mysterious how belief in a top-down fashion could cause people with schizophrenia to be worse at fast error correction than normal controls, to be better at tickling themselves than normal controls, and to have an increased response to the sound of their own voice.On the other hand, although the skin conductance response (SCR) evidence suggests a bottom-up approach to the Capgras delusion, it does not explain the character of the subjective experience that is hypothesized to give rise to the delusional belief: reduced SCR is not part of the experience itself (thanks to Ian Gold for discussion of this). Something more is required to give a full account of the type of experience that gives rise to the delusion. Further, as they stand, most bottom-up accounts are unable to account for why reality testing fails for beliefs based on these experiences.Neither rationalism nor empiricism on their own seem able to address the conceptual questions while paying... (shrink)

Recent experimental work suggests that the concept of contextual fields should be generalized to allow the modulation of local information extraction by both external and internal context. The external context relates to the coherent information of the stimulus; the internal context refers to the parts of this information which are relevant for behavior. This dual interaction, present at every level of the hierarchy, requires a fundamental unit of processing more complex than a single neuron appears today. We argue that (...) the cortical column supplies the required mechanisms for a separate top-down and bottom-up processing and allows for interaction without destructive cross-talk. This flexibility might explain why the same basic architecture of a cortical column is used in the whole isocortex. (shrink)

Skeletal myoblasts have their origin early in embryogenesis within specific somites. Determined myoblasts are committed to a myogenic fate; however, they only differentiate and express a muscle‐specific phenotype after they have received the appropriate environmental signals. Once proliferating myoblasts enter the differentiation programme they withdraw from the cell cycle and form post‐mitotic multinucleated myofibres (myogenesis); this transformation is accompanied by muscle‐specific gene expression. Muscle development is associated with complex and diverse protein isoform transitions, generated by differential gene expression and mRNA (...) splicing. The myofibres are in a state of dynamic adaptation in response to hormones, mechanical activity and motor innervation, which modulate differential gene expression and splicing during this functional acclimatisation. This review will focus on the profound effects of thyroid hormone on skeletal muscle, which produce alterations in gene and isoform expression, biochemical properties and morphological features that precipitate in modified contractile/mechanical characteristics. Insight into the molecular events that control these events was provided by the recent characterisation of the MyoD gene family, which encodes helix‐loop‐helix proteins; these activate muscle‐specific transcription and serve as targets for a variety of physiological stimuli. The current hypothesis on hormonal regulation of myogenesis is that thyroid hormones (1) directly regulate the myoD and contractile protein gene families, and (2) induce thyroid hormone receptor‐transcription factor interactions critical to gene expression. (shrink)

Our understanding of body ownership largely relies on the Rubber Hand Illusion (RHI) paradigm where synchronous stroking of the real and fake hands leads to an illusion of ownership of RH provided its physical, anatomical, and spatial plausibility. Self-attribution of a fake hand also occurs during visuomotor synchrony, when the visual feedback of self-initiated movements follows the trajectory of the instantiated motor command. In both cases, the experience of ownership is established through bottom-up integration and top-down prediction of multisensory (...) (proximodistal) cues within the peripersonal space. It seems, however, that depending on whether the signals are externally or self-generated, top-down expectation signals are qualitatively different. On the one hand, in RHI, the sensory correlations are modulated by empirically induced priors about the internal model of the body. On the other hand, in mRHI, body ownership is actively shaped by processes allowing for continuous comparison between the actual and predicted sensory consequences of the actions. Ample research demonstrates that the differential processing of the predicted and the actual reafferent information is addressed by the central nervous system via an internal Forward Model (FM). Indeed, results from mRHI suggest that in action-contexts mechanism underlying body ownership could be similar to the FM. Crucially FMs integrate across all sensory input including not only proximodistal (visuomotor) but also purely distal sensory signals (visuoauditory). Thus if body ownership results from a consistency of FM, it would be affected by the (in)congruency of purely distal signals provided that they inform about the action-consequences relevant to the task. Here we explicitly address this question. To test our hypothesis, we devise an embodied VR-based task where action outcomes were signaled by distinct auditory cues. By manipulating the cues with respect to their spatial, temporal and semantic congruency, we show that purely distal feedback violating predictions about action outcomes compromises both body ownership and performance. These results demonstrate that body ownership is influenced by cues which not only pertain to the body itself but also those arising outside of the body, and suggest that in goal-oriented tasks body ownership might result from the consistency of forward models. (shrink)

Accounts of mechanistic explanation have emphasized the importance of looking down—decomposing a mechanism into its parts and operations. Using research on visual processing as an exemplar, I illustrate how productive such research has been. But once multiple components of a mechanism have been identified, researchers also need to figure out how it is organized—they must look around and determine how to recompose the mechanism. Although researchers often begin by trying to recompose the mechanism in terms of sequential operations, they (...) frequently find that the components of a mechanism interact in complex ways involving positive and negative feedback and that the organization often exhibits highly interactive local networks linked by a few long-range connections (small-worlds organization) and power law distributions of connections. The mechanisms are themselves active systems that are perturbed by inputs but not set in motion by them. Researchers also need to look up —situate a mechanism in its context, which may be a larger mechanism that modulates its behavior. When looking down is combined with looking around and up, mechanistic research results in an integrated, multi-level perspective. (shrink)

Many studies have revealed the top-down modulation on unconscious processing. However, there is little research about how category-selective attention could modulate the unconscious processing. In the present study, using functional magnetic resonance imaging , the results showed that category-selective attention modulated unconscious face/tool processing in the middle occipital gyrus . Interestingly, MOG effects were of opposed direction for face and tool processes. During unconscious face processing, activation in MOG decreased under the face-selective attention compared with tool-selective attention. This (...) result was in line with the predictive coding theory. During unconscious tool processing, however, activation in MOG increased under the tool-selective attention compared with face-selective attention. The different effects might be ascribed to an interaction between top-down category-selective processes and bottom-up processes in the partial awareness level as proposed by Kouider, De Gardelle, Sackur, and Dupoux . Specifically, we suppose an “excessive activation” hypothesis. (shrink)

Upon hearing a scalar adjective in a definite referring expression such as “the big…,” listeners typically make anticipatory eye movements to an item in a contrast set, such as a big glass in the context of a smaller glass. Recent studies have suggested that this rapid, contrastive interpretation of scalar adjectives is malleable and calibrated to the speaker's pragmatic competence. In a series of eye‐tracking experiments, we explore the nature of the evidence necessary for the modulation of pragmatic inferences (...) in language comprehension, focusing on the complementary roles of top–down information ‐ (knowledge about the particular speaker's pragmatic competence) and bottom‐up cues (distributional information about the use of scalar adjectives in the environment). We find that bottom‐up evidence alone (e.g., the speaker says “the big dog” in a context with one dog), in large quantities, can be sufficient to trigger modulation of the listener's contrastive inferences, with or without top‐down cues to support this adaptation. Further, these findings suggest that listeners track and flexibly combine multiple sources of information in service of efficient pragmatic communication. (shrink)

Tactile perception is often impaired during movement. The present study investigated whether such sensory suppression also occurs during back movements, and whether this would be modulated by attention. In two tactile detection experiments, participants simultaneously engaged in a movement task, in which they executed a back-bending movement, and a perceptual task, consisting of the detection of subtle tactile stimuli administered to their upper or lower back. The focus of participants’ attention was manipulated by raising the probability that one of the (...) back locations would be stimulated. The results revealed that tactile detection was suppressed during the execution of the back movements. Furthermore, the results of Experiment 2 revealed that when the stimulus was always presented to the attended location, tactile suppression was substantially reduced, suggesting that sensory suppression can be modulated by top-down attentional processes. The potential of this paradigm for studying tactile information processing in clinical populations is discussed. (shrink)

Stroke remains one of the leading causes of various disabilities, including debilitating motor and language impairments. Though various treatments exist, post-stroke impairments frequently become chronic, dramatically reducing daily life quality, and requiring specific rehabilitation. A critical goal of chronic stroke rehabilitation is to induce, usually through behavioral training, experience-dependent plasticity processes in order to promote functional recovery. However, the efficiency of such interventions is typically modest, and very little is known regarding the neural dynamics underpinning recovery processes and possible biomarkers (...) of their efficiency. Some studies have emphasized specific alterations of excitatory–inhibitory balance within distributed neural networks as an important recovery correlate. Neural processes sensitive to these alterations, such as task-dependent oscillatory activity in beta as well as alpha bands, may be candidate biomarkers of chronic stroke functional recovery. In this review, we discuss the results of studies on motor and language recovery with a focus on oscillatory processes centered around the beta band and their modulations during functional recovery in chronic stroke. The discussion is based on a framework where task-dependent modulations of beta and alpha oscillatory activity, generated by the deep cortical excitatory–inhibitory microcircuits, serve as a neural mechanism of domain-general top-down control processes. We discuss the findings, their limitations, and possible directions for future research. (shrink)

While much has been written about whether visual perception is cognitively penetrable, the analogous question with respect to auditory perception has received very little attention. Here we argue that instances of top-down modulation of auditory processing, although extensive, do not constitute cases of cognitive penetration of auditory perception since the changes in the phenomenology of auditory perception caused by top-down influences cannot plausibly be attributed to the listeners’ discursive thoughts.

Recent data indicate that under a specific posthypnotic suggestion to circumvent reading, highly suggestible subjects successfully eliminated the Stroop interference effect. The present study examined whether an optical explanation could account for this finding. Using cyclopentolate hydrochloride eye drops to pharmacologically prevent visual accommodation in all subjects, behavioral Stroop data were collected from six highly hypnotizables and six less suggestibles using an optical setup that guaranteed either sharply focused or blurred vision. The highly suggestibles performed the Stroop task when naturally (...) vigilant, under posthypnotic suggestion not to read, and while visually blurred; the less suggestibles ran naturally vigilant, while looking away, and while visually blurred. Although visual accommodation was precluded for all subjects, posthypnotic suggestion effectively eliminated Stroop interference and was comparable to looking away in controls. These data strengthen the view that Stroop interference is neither robust nor inevitable and support the hypothesis that posthypnotic suggestion may exert a top-down influence on neural processing. (shrink)

Recent data indicate that under a specific posthypnotic suggestion to circumvent reading, highly suggestible subjects successfully eliminated the Stroop interference effect. The present study examined whether an optical explanation could account for this finding. Using cyclopentolate hydrochloride eye drops to pharmacologically prevent visual accommodation in all subjects, behavioral Stroop data were collected from six highly hypnotizables and six less suggestibles using an optical setup that guaranteed either sharply focused or blurred vision. The highly suggestibles performed the Stroop task when naturally (...) vigilant, under posthypnotic suggestion not to read, and while visually blurred; the less suggestibles ran naturally vigilant, while looking away, and while visually blurred. Although visual accommodation was precluded for all subjects, posthypnotic suggestion effectively eliminated Stroop interference and was comparable to looking away in controls. These data strengthen the view that Stroop interference is neither robust nor inevitable and support the hypothesis that posthypnotic suggestion may exert a top-down influence on neural processing. (shrink)

Mirror-touch synaesthesia is a condition where observing touch to another’s body induces a subjective tactile sensation on the synaesthetes body. The present study explores which characteristics of the inducing stimulus modulate the synaesthetic touch experience. Fourteen mirror-touch synaesthetes watched videos depicting a touch event while indicating whether the video induced a tactile sensation, on which side of their body they felt this sensation and the intensity of the experienced sensation. Results indicate that the synaesthetes experience stronger tactile sensations when observing (...) touch to real bodies, whereas observing touch to dummy bodies, pictures of bodies and disconnected dummy body parts elicited weaker sensations. These results suggest that mirror-touch synaesthesia is not entirely bottom-up driven, but top-down information, such as knowledge about real and dummy body parts, also modulate the intensity of the experience. (shrink)

Research has demonstrated that people readily pay more attention to negative than to positive and/or neutral stimuli. However, evidence from recent studies indicated that such an attention bias to negative information is not obligatory but sensitive to various factors. Two experiments using intergroup evaluative tasks (Study 1: a gender-related groups evaluative task and Study 2: a minimal-related groups evaluative task) was conducted to determine whether motivation to strive for a positive social identity - a part of one's self-concept - drives (...) attention toward affective stimuli. Using the P1 component of event-related brain potentials (ERPs) as a neural index of attention, we confirmed that attention bias toward negative stimuli is not mandatory but it can depend on a motivational focus on affective outcomes. Results showed that social identity-based motivation is likely to bias attention toward affectively incongruent information. Thereby, early onset processes - reflected by the P1 component - appeared susceptible to top-down attentional influences induced by the individual's motivation to strive for a positive social identity. (shrink)

Previous research has demonstrated that duration of implied motion (IM) was dilated, whereas hMT+ activity related to perceptual processes on IM stimuli could be modulated by their motion coherence. Based on these findings, the present study aimed to examine whether subjective time perception of IM stimuli would be influenced by varying coherence levels. A temporal bisection task was used to measure the subjective experience of time, in which photographic stimuli showing a human moving in four directions (left, right, toward, or (...) away from the viewer) were presented as probe stimuli. The varying coherence of these IM stimuli was manipulated by changing the percentage of pictures implying movement in one direction. Participants were required to judge whether the duration of probe stimulus was more similar to the long or short pre-presented standard duration. As predicted, the point of subjective equality was significantly modulated by the varying coherence of the IM stimuli, but not for no-IM stimuli. This finding suggests that coherence level might be a key mediating factor for perceived duration of IM images, and top-down perceptual stream from inferred motion could influence subjective experience of time perception. (shrink)

Angry faces have been shown to be detected more efficiently in a crowd of distractors compared to happy faces, known as the anger superiority effect (ASE). The present study investigated whether the ASE could be modified by top-down manipulation of working memory (WM), in central and peripheral visual fields. In central vision, participants held a colour in WM for a final memory test while simultaneously performing a visual search task that required them to determine whether a face showed a (...) different expression from other coloured faces. The colour held in WM matched either the colour of the target face (target-matching), the colour of a distractor face (distractor-matching), or neither (non-matching). Results showed that the ASE was observed when the probability of target-matching trials was low. However, when the top-down WM effect was strengthened by raising the probability of target-matching trials, the ASE in the target-matching condition was completely eliminated. Intriguingly, when the visual search task was substituted by a peripheral crowding task, similar results to central vision were found in the target-matching condition. Taken together, our findings indicate that the ASE is subject to the top-down WM effect, regardless of the visual field. (shrink)

We argue that intelligible appeals to interlevel causes (top-down and bottom-up) can be understood, without remainder, as appeals to mechanistically mediated effects. Mechanistically mediated effects are hybrids of causal and constitutive relations, where the causal relations are exclusively intralevel. The idea of causation would have to stretch to the breaking point to accommodate interlevel causes. The notion of a mechanistically mediated effect is preferable because it can do all of the required work without appealing to mysterious interlevel causes. When (...) interlevel causes can be translated into mechanistically mediated effects, the posited relationship is intelligible and should raise no special philosophical objections. When they cannot, they are suspect. (shrink)

Prominent models of attentional control assert a dichotomy between top-down and bottom-up control, with the former determined by current selection goals and the latter determined by physical salience. This theoretical dichotomy, however, fails to explain a growing number of cases in which neither current goals nor physical salience can account for strong selection biases. For example, equally salient stimuli associated with reward can capture attention, even when this contradicts current selection goals. Thus, although 'top-down' sources of bias are (...) sometimes defined as those that are not due to physical salience, this conception conflates distinct - and sometimes contradictory - sources of selection bias. We describe an alternative framework, in which past selection history is integrated with current goals and physical salience to shape an integrated priority map. (shrink)

The distinction between top-down and bottom-up effects is widely relied on in experimental psychology. However, there is an important problem with the way it is normally defined. Top-down effects are effects of previously-stored information on processing the current input. But on the face of it that includes the information that is implicit in the operation of any psychological process – in its dispositions to transition from some types of representational state to others. This paper suggests a way to (...) distinguish information stored in that way from the kind of influence of prior information that psychologists are concerned to classify as a top-down effect. So-drawn, the distinction is not just of service to theoretical psychology. Asking about the extent of top-down processing is one way to pose some of the questions at issue in philosophical debates about cognitive penetrability – about the extent of the influence of cognitive states on perception. The existence of a theoretically-useful perception-cognition distinction has come under pressure, but even if it has to be abandoned, some of the concerns addressed in the cognitive penetrability literature can be recaptured by asking about the extent of top-down influences on any given psychological process. That formulation is more general, since it can be applied to any psychological process, not just those that are paradigmatically perceptual. (shrink)

This book presents the latest research, conducted by leading philosophers and scientists from various fields, on the topic of top-down causation. The chapters combine to form a unique, interdisciplinary perspective, drawing upon George Ellis's extensive research and novel perspectives on topics including downwards causation, weak and strong emergence, mental causation, biological relativity, effective field theory and levels in nature. The collection also serves as a Festschrift in honour of George Ellis' 80th birthday. The extensive and interdisciplinary scope of this (...) book makes it vital reading for anyone interested in the work of George Ellis and current research on the topics of causation and emergence. (shrink)

Our ability to rapidly distinguish new from already stored information is important for behavior and decision making, but the underlying processes remain unclear. Here, we tested the hypothesis that contextual cues lead to a preselection of information and, therefore, faster recognition. Specifically, on the basis of previous modeling work, we hypothesized that recognition time depends on the amount of relevant content stored in long-term memory, i.e., set size, and we explored possible age-related changes of this relationship in older humans. In (...) our paradigm, subjects learned by heart four different word lists written in different colors. On the day of testing, a color cue indicated with a probability of 50% that a subsequent word might be from the corresponding list or from a list of new words. The old/new status of the word had to be distinguished via button press. As a main finding, we can show in a sample of n = 49 subjects, including 26 younger and 23 older humans, that response times increased linearly and logarithmically as a function of set size in both age groups. Conversely, corrected hit rates decreased as a function of set size with no statistically significant differences between both age groups. As such, our findings provide empirical evidence that contextual information can lead to a preselection of relevant information stored in long-term memory to promote efficient recognition, possibly by cyclical top-down and bottom-up processing. (shrink)

The philosophy of mathematics of the last few decades is commonly distinguished into mainstream and maverick, to which a ‘third way’ has been recently added, the philosophy of mathematical practice. In this paper the limitations of these trends in the philosophy of mathematics are pointed out, and it is argued that they are due to the fact that all of them are based on a top-down approach, that is, an approach which explains the nature of mathematics in terms of (...) some general unproven assumption. As an alternative, a bottom-up approach is proposed, which explains the nature of mathematics in terms of the activity of real individuals and interactions between them. This involves distinguishing between mathematics as a discipline and the mathematics embodied in organisms as a result of biological evolution, which however, while being distinguished, are not opposed. Moreover, it requires a view of mathematical proof, mathematical definition and mathematical objects which is alternative to the top-down approach. (shrink)

This paper explores the interaction between implicit and explicit processes during skill learning, in terms of top-down learning (that is, learning that goes from explicit to implicit knowledge) versus bottom-up learning (that is, learning that goes from implicit to explicit knowledge). Instead of studying each type of knowledge (implicit or explicit) in isolation, we stress the interaction between the two types, especially in terms of one type giving rise to the other, and its effects on learning. The work presents (...) an integrated model of skill learning that takes into account both implicit and explicit processes and both top-down and bottom-up learning. We examine and simulate human data in the Tower of Hanoi task. The paper shows how the quantitative data in this task may be captured using either top-down or bottom-up approaches, although top-down learning is a more apt explanation of the human data currently available. These results illustrate the two different directions of learning (top-down versus bottom-up), and thereby provide a new perspective on skill learning. Ó 2003 Elsevier B.V. All rights reserved. (shrink)

This study adds to the growing research exploring the consequences of knowledge hiding in organizations. Drawing from the social exchange theory and the norm of reciprocity, this paper examines the direct and indirect—via distrust in supervisor—relationships between supervisor knowledge hiding and supervisee organizational citizenship behavior directed at the supervisor in the context of the Middle East. Using a supervisor–supervisee dyadic design, two-source data were obtained from 317 employees of 41 Saudi firms. The findings suggest that supervisees’ distrust in their supervisors (...) mediates the significant and negative relationship between SKH and supervisees’ OCB-S. Furthermore, the significant and positive relationship between SKH and distrust in supervisor is more pronounced for foreign workers than for local workers. This study provides empirical support and a better understanding of the existence and consequences of SKH for local and foreign workers and also discusses the theoretical and practical implications of the findings. (shrink)