Taking control of reflexive social attention

Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also the case that top-down factors may modulate the activation of IT cells. Here we examined behaviorally whether reflexive social orienting is purely automatic or sensitive to top-down modulation. Participants were shown an ambiguous stimulus that could be perceived either as representing EYES or a CAR. In we demonstrated between groups that an automatic shift of attention, equivalent to that triggered by a schematic FACE, occurred only when the stimulus was referred to as possessing EYES. In all participants received the EYES and CAR conditions. When the stimulus was first referred to as a CAR and then as EYES, an attentional shift was only present for the EYES condition. However, when the stimulus was first referred to as possessing EYES, and then later as a CAR, attentional shifts were observed for both conditions. These data indicate that the emergence of a reflexive social attention effect is influenced by top-down mechanisms but in an asymmetrical manner. Top-down processes appear to be effective for triggering IT involvement, that is, for perceiving a stimulus as a face, which produces the social attention effect. But top-down mechanisms are ineffective once IT involvement has been triggered. That is, once a stimulus has been seen as having eyes, it continues to be seen that way, and accordingly, the social attention effect persists.     

All Finitely Axiomatizable Tense Logics of Linear Time Flows Are CoNP-complete

We prove that all finitely axiomatizable tense logics with temporal operators for ‘always in the future’ and ‘always in the past’ and determined by linear fows time are coNP-complete. It follows, for example, that all tense logics containing a density axiom of the form ■ⁿ⁺¹_F p → ⁿ_F p, for some n ≥ 0, are coNP-complete. Additionally, we prove coNP-completeness of all ∩-irreducible tense logics. As these classes of tense logics contain many Kripke incomplete bimodal logics, we obtain many natural examples of Kripke incomplete normal bimodal logics which are nevertheless coNP-complete.     

Disruption of temporally organized behavior by morphine

Four pigeons pecked keys in two different procedures commonly used in the study of timing, or temporal discrimination. Sessions consisted of 40 trials. During half of the trials, two keys were presented for 50 s. Left-key pecks were reinforced according to a variable-interval 67.86-s schedule during the first 25 s of the trial, and right-key pecks were not reinforced. During the second 25 s of the trial, right-key pecks were reinforced according to the same schedule, and left-key pecks were not reinforced. In the other half of the 40-trial session, the center key was presented. The majority of these trials arranged fixed-interval 2.5-s schedules. Occasionally a probe, or peak-interval, trial was presented. These trials were 100 s in duration and terminated without reinforcement. These two procedures were used to examine the effects of morphine on indexes of timing and on patterns of responding. Morphine altered behavior in a race-dependent manner in both procedures. Low baseline (saline) response rates were increased following morphine administration, and high baseline rates were either unaffected or decreased slightly. Rate-dependent effects appeared as leftward shifts in the timing index for two-key trials and decreases in the index of curvature for fixed-interval trials. Despite large changes in response rates, no consistent shift of the peak time was observed during peak-interval trials. These results are discussed primarily in terms of rate dependency; that is, rates of responding following drug administration tend to be determined in large part by rates of responding under baseline conditions.     

Temporal processing and phonological impairment in dyslexia: effect of phoneme lengthening on order judgment of two consonants

The evidence of supporting phonological deficit as a cause of developmental dyslexia has been accumulating rapidly over the past 2 decades, yet the exact mechanisms underlying this deficit remain controversial. Some authors assume that a temporal processing deficit is the source of the phonological disorder observed in dyslexic children. Others maintain that the phonological deficit in dyslexia is basically linguistic, not acoustic, in nature. Three experiments were conducted and tested the impact of the temporal alteration and the impact of complex syllabic structure on consonant order judgments. Thirteen phonological dyslexics (age 10-13) and 10 controls matched for chronologial age were compared on a Temporal Order Judgment (TOJ) task using the succession of two consonants (/p/ /s/) within a cluster. In order to test the possible relevance of the temporal deficit hypothesis, the task also included two additional conditions where either the two stimuli were artificially slowed or two phonological structures were opposed (CCV and CVCV). As expected, the TOJ performance was significantly poorer in dyslexics than in controls. Moreover, in the "slowed speech" condition dyslexics' performance improved to reach the normal controls' level, whereas manipulating the phonological structure complexity provided no significant improvement. Finally dyslexics' performances, especially on the slowed condition, were found correlated with several tests of phonological processing. These results lend support to the general temporal deficit theory of dyslexia.     

Learning related modulation of functional retrieval networks in man

The medial temporal lobe has been implicated in studies of episodic memory tasks involving spatio-temporal context and object-location conjunctions. We have previously demonstrated that an increased level of practice in a free-recall task parallels a decrease in the functional activity of several brain regions, including the medial temporal lobe, the prefrontal, the anterior cingulate, the anterior insular, and the posterior parietal cortices, that in concert demonstrate a move from elaborate controlled processing towards a higher degree of automaticity. Here we report data from two experiments that extend these initial observations. We used a similar experimental approach but probed for effects of retrieval paradigms and stimulus material. In the first experiment we investigated practice related changes during recognition of object-location conjunctions and in the second during free-recall of pseudo-words. Learning in a neural network is a dynamic consequence of information processing and network plasticity. The present and previous PET results indicate that practice can induce a learning related functional restructuring of information processing. Different adaptive processes likely subserve the functional re-organisation observed. These may in part be related to different demands for attentional and working memory processing. It appears that the role(s) of the prefrontal cortex and the medial temporal lobe in memory retrieval are complex, perhaps reflecting several different interacting processes or cognitive components. We suggest that an integrative interactive perspective on the role of the prefrontal and medial temporal lobe is necessary for an understanding of the processing significance of these regions in learning and memory. It appears necessary to develop elaborated and explicit computational models for prefrontal and medial temporal functions in order to derive detailed empirical predictions, and in combination with an efficient use and development of functional neuroimaging approaches, to further the understanding of the processing significance of these regions in memory.     

The Declarative/Procedural Model of Lexicon and Grammar

Our use of language depends upon two capacities: a mental lexicon of memorized words and a mental grammar of rules that underlie the sequential and hierarchical composition of lexical forms into predictably structured larger words, phrases, and sentences. The declarative/procedural model posits that the lexicon/grammar distinction in language is tied to the distinction between two well-studied brain memory systems. On this view, the memorization and use of at least simple words (those with noncompositional, that is, arbitrary form-meaning pairings) depends upon an associative memory of distributed representations that is subserved by temporal-lobe circuits previously implicated in the learning and use of fact and event knowledge. This declarative memory system appears to be specialized for learning arbitrarily related information (i.e., for associative binding). In contrast, the acquisition and use of grammatical rules that underlie symbol manipulation is subserved by frontal/basal-ganglia circuits previously implicated in the implicit (nonconscious) learning and expression of motor and cognitive skills and habits (e.g., from simple motor acts to skilled game playing). This procedural system may be specialized for computing sequences. This novel view of lexicon and grammar offers an alternative to the two main competing theoretical frameworks. It shares the perspective of traditional dual-mechanism theories in positing that the mental lexicon and a symbol-manipulating mental grammar are subserved by distinct computational components that may be linked to distinct brain structures. However, it diverges from these theories where they assume components dedicated to each of the two language capacities (that is, domain-specific) and in their common assumption that lexical memory is a rote list of items. Conversely, while it shares with single-mechanism theories the perspective that the two capacities are subserved by domain-independent computational mechanisms, it diverges from them where they link both capacities to a single associative memory system with broad anatomic distribution. The declarative/procedural model, but neither traditional dual- nor single-mechanism models, predicts double dissociations between lexicon and grammar, with associations among associative memory properties, memorized words and facts, and temporal-lobe structures, and among symbol-manipulation properties, grammatical rule products, motor skills, and frontal/basal-ganglia structures. In order to contrast lexicon and grammar while holding other factors constant, we have focused our investigations of the declarative/procedural model on morphologically complex word forms. Morphological transformations that are (largely) unproductive (e.g., in go—went, solemn—solemnity) are hypothesized to depend upon declarative memory. These have been contrasted with morphological transformations that are fully productive (e.g., in walk—walked, happy—happiness), whose computation is posited to be solely dependent upon grammatical rules subserved by the procedural system. Here evidence is presented from studies that use a range of psycholinguistic and neurolinguistic approaches with children and adults. It is argued that converging evidence from these studies supports the declarative/procedural model of lexicon and grammar.     

TMS to the “occipital face area” affects recognition but not categorization of faces

The human cortical system for face perception is comprised of a network of connected regions including the middle fusiform gyrus (“fusiform face area” or FFA), the inferior occipital cortex (“occipital face area” or OFA), and the superior temporal sulcus. The traditional hierarchical feedforward model of visual processing suggests information flows from early visual cortex to the OFA for initial face feature analysis to higher order regions including the FFA for identity recognition. However, patient data suggest an alternative model. Patients with acquired prosopagnosia, an inability to visually recognize faces, have been documented with lesions to the OFA but who nevertheless show face-selective activation in the FFA. Moreover, their ability to categorize faces remains intact. This suggests that the FFA is not solely responsible for face recognition and the network is not strictly hierarchical, but may be organized in a reverse hierarchical fashion. We used transcranial magnetic stimulation (TMS) to temporarily disrupt processing in the OFA in neurologically-intact individuals and found participants’ ability to categorize intact versus scrambled faces was unaffected, however face identity discrimination was significantly impaired. This suggests that face categorization but not recognition can occur without the “earlier” OFA being online and indicates that “lower level” face category processing may be assumed by other intact face network regions such as the FFA. These results are consistent with the patient data and support a non-hierarchical, global-to-local model with re-entrant connections between the OFA and other face processing areas.     

Studying Early Adolescents' Academic Motivation,Social-Emotional Functioning,and Engagement in Learning: Variable- and Person-Centered Approaches

This study used variable- and person-centered data analytic techniques to examine how early adolescents' academic motivation and social-emotional functioning were associated with their self-reported cognitive and behavioral engagement in the middle school classroom. Regression results showed that both motivational and mental health constructs contributed to the prediction of individual differences in classroom engagement. Person-centered analyses revealed between group variation in classroom engagement as a function of differing patterns of motivation and mental health among different subgroups of adolescents. Convergent and complementary information on these subgroups was provided by using two different grouping approaches. Findings are discussed in terms of broad patterns of promise or problems during early adolescence.