Factors affecting processing mode in visual search

Visual search was studied under a variety of conditions to clarify some differences among the results of previous investigations and to provide a testing ground for models of visual information processing. Display configuration, target and field composition, exposure duration, and display size (up to 16 elements) were among the parameters investigated. In some conditions, mean reaction time was essentially invariant with display size, while in other conditions it increased substantially and linearly with display size. Current models of visual information processing were evaluated in the light of these and previous findings; all were found wanting. The data seem to demand a system subject to flexible cognitive control processes.     

Selective imitation of the passive construction through modeling

Six 4- to 5-yr-old subjects were exposed to five sessions in which an adult model used passive sentences to describe a set of modeling stimuli. Probe stimuli, which the subjects were asked to describe without benefit of modeling and without selective reinforcement were interspersed among modeling stimuli. A matched group of control subjects received probletrials but no modeling trials. Both groups of subjects were subsequently tested on their ability to comprehend active and passive sentence forms. Every subject in the experimental group produced passive sentences on probe trials even though there was considerable variability in the number of passives produced. No control subject produced passives. The modeling procedure increased the comprehension scores of the experimental group above those of the control group though the scores of both groups were above chance. The results were contrasted with earlier studies in which modeling was ineffective in producing passive usage and in which comprehension of the passive was not demonstrated by even older children.     

LTP in hippocampal area CA1 is induced by burst stimulation over a broad frequency range centered around delta

Long-term potentiation (LTP) is typically studied using either continuous high-frequency stimulation or theta burst stimulation. Previous studies emphasized the physiological relevance of theta frequency; however, synchronized hippocampal activity occurs over a broader frequency range. We therefore tested burst stimulation at intervals from 100 msec to 20 sec (10 Hz to 0.05 Hz). LTP at Schaffer collateral–CA1 synapses was obtained at intervals from 100 msec to 5 sec, with maximal LTP at 350–500 msec (2–3 Hz, delta frequency). In addition, a short-duration potentiation was present over the entire range of burst intervals. We found that N-methyl-d-aspartic acid (NMDA) receptors were more important for LTP induction by burst stimulation, but L-type calcium channels were more important for LTP induction by continuous high-frequency stimulation. NMDA receptors were even more critical for short-duration potentiation than they were for LTP. We also compared repeated burst stimulation with a single primed burst. In contrast to results from repeated burst stimulation, primed burst potentiation was greater when a 200-msec interval (theta frequency) was used, and a 500-msec interval was ineffective. Whole-cell recordings of postsynaptic membrane potential during burst stimulation revealed two factors that may determine the interval dependence of LTP. First, excitatory postsynaptic potentials facilitated across bursts at 500-msec intervals but not 200-msec or 1-sec intervals. Second, synaptic inhibition was suppressed by burst stimulation at intervals between 200 msec and 1 sec. Our data show that CA1 synapses are more broadly tuned for potentiation than previously appreciated.Long-term potentiation (LTP) is used as a model for studying synaptic events during learning and memory (Bliss and Collingridge 1993; Morris 2003; Lynch 2004). At most synapses, LTP is triggered by postsynaptic Ca²⁺ influx through N-methyl-d-aspartic acid (NMDA) glutamate receptors (Collingridge et al. 1983; Harris et al. 1984; Herron et al. 1986) and, under some conditions, through L-type voltage-gated Ca²⁺ channels (Grover and Teyler 1990, 1994; Morgan and Teyler 1999). LTP was discovered in the dentate gyrus (Bliss and Lomo 1973) following several seconds of 10–100 Hz stimulation of the perforant path. Since then, many LTP studies have used similar long, high-frequency stimulation (HFS) protocols, most typically 100 Hz, 1 sec (Bliss and Collingridge 1993). Although effective, HFS does not resemble physiological patterns of activity (Albensi et al. 2007). Patterned stimulation resembling physiological activity, in particular theta burst stimulation, is also effective for LTP induction (Larson et al. 1986; Staubli and Lynch 1987; Capocchi et al. 1992; Nguyen and Kandel 1997). Theta burst stimulation consists of short bursts (4–5 stimuli at 100 Hz) repeated at 5 Hz, which lies within the hippocampal theta frequency range (4–12 Hz) (Bland 1986; Buzsáki 2002). Primed burst stimulation, another form of patterned stimulation, involves delivery of a priming stimulus followed by a single short burst (Larson and Lynch 1986; Rose and Dunwiddie 1986). The temporal requirements for primed burst LTP are quite precise (Diamond et al. 1988; Greenstein et al. 1988; Larson and Lynch 1989): Intervals less than 140 msec or greater than 200 msec are ineffective.The mechanisms underlying theta frequency-dependent LTP have been studied primarily using the primed burst protocol (Larson and Lynch 1986, 1988, 1989; Pacelli et al. 1989; Davies and Collingridge 1996). Activation of GABA_B autoreceptors during the priming stimulus suppresses GABA release during the following burst (Davies et al. 1990; Lambert and Wilson 1994; Olpe et al. 1994), allowing greater postsynaptic depolarization (Larson and Lynch 1986; Pacelli et al. 1989) and more effective NMDA receptor activation (Davies and Collingridge 1996). Consequently, temporal requirements for primed burst potentiation match the time course of GABA_B autoreceptor-mediated suppression of GABA release (Davies et al. 1990; Davies and Collingridge 1993; Mott et al. 1993).Besides theta, hippocampal activity is observed at other frequencies, notably sharp waves (0.01–5 Hz) (Buzsáki 1986, 1989; Suzuki and Smith 1987) and low-frequency oscillations (≤1 Hz) (Wolansky et al. 2006; Moroni et al. 2007). These lower frequencies dominate during slow wave sleep (Buzsáki 1986; Suzuki and Smith 1987; Wolansky et al. 2006; Moroni et al. 2007), and contribute to hippocampal memory processing (Buzsáki 1989; Pennartz et al. 2002). While synchronized population activity over frequencies from <1 Hz to 12 Hz is associated with hippocampal memory function, previous LTP studies have focused on theta. We therefore investigated burst stimulation at frequencies from 0.05 Hz to 10 Hz. We found that CA1 synapses potentiate to some degree over this entire range and that maximal potentiation occurs around delta frequency rather than theta.     

Propositional quantifiers

Summary In discussing propositional quantifiers we have considered two kinds of variables: variables occupying the argument places of connectives, and variables occupying the argument places of predicates.We began with languages which contained the first kind of variable, i.e., variables taking sentences as substituends. Our first point was that there appear to be no sentences in English that serve as adequate readings of formulas containing propositional quantifiers. Then we showed how a certain natural and illuminating extension of English by prosentences did provide perspicuous readings. The point of introducing prosentences was to provide a way of making clear the grammar of propositional variables: propositional variables have a prosentential character — not a pronominal character. Given this information we were able to show, on the assumption that the grammar of propositional variables in philosopher's English should be determined by their grammar in formal languages (unless a separate account of their grammar is provided), that propositional variables can be used in a grammatically and philosophically acceptable way in philosophers' English. According to our criteria of well-formedness Carnap's semantic definition of truth does not lack an essential predicate - despite arguments to the contrary. It also followed from our account of the prosentential character of bound propositional variables that in explaining propositional quantification, sentences should not be construed as names.One matter we have not discussed is whether such quantification should be called propositional, sentential, or something else. As our variables do not range over (they are not terms) either propositions, or sentences, each name is inappropriate, given the usual picture of quantification. But we think the relevant question in this context is, are we obtaining generality with respect to propositions, sentences, or something else?Because people have argued that all bound variables must have a pronominal character, we presented and discussed in the third section languages in which the variables take propositional terms as substituends. In our case we included names of propositions, that-clauses, and names of sentences in the set of propositional terms. We made a few comparisons with the languages discussed in the second section. We showed among other things how a truth predicate could be used to obtain generality. In contrast, the languages of the second section, using propositional variables, obtain generality without the use of a truth predicate.Special thanks are due to Nuel D. Belnap, Jr., who has given me much valuable assistance with the preparation of this paper. I also thank Alan Ross Anderson, Joseph Camp, Jr., Steven Davis, and Wilfrid Sellars for suggestions and corrections.The preparation of this paper was partly supported by a NSF grant.     

The effects of redundant communications on the behavior of listeners: Does a picture need a thousand words?

Using a referential communication paradigm, two types of, informative messages, contrastive and redundant, were compared developmentally in terms of their relative effects on the accuracy of listeners' responses as a function of task variables. Contrastive messages contained the minimal information necessary to distinguish a referent from a nonreferent. Redundant messages contained additional information. We predicted that redundant messages would be more effective than contrastive ones when the stimulus array was too complex for a listener to notice all aspects of it in the allotted time. Also manipulated were the order of presentation of the message and array and the delay between the two in order to determine how these factors would contribute to task complexity. Subjects were first-and third-graders and college students. The stimuli were drawings of cartoonlike figures. The results confirmed our predictions for the older subjects but not for the younger ones. The discussion of the data centered on why the picture-message sequence, was a more difficult sequence than the message-picture one for all age groups.     

The development of communication: Attribute variation leads to contrast failure

Groups of 5-year-olds in two experiments described multidimensional triangles for a listener. The attribute differentiating referent triangles from nonreferent triangles in Experiment I was constant across trials for the simple condition group, while any one of three attributes was distinctive on a given trial for the complex condition group. One-adjective messages by subjects in the simple condition were virtually always informative; in the complex group, such messages were predominantly ambiguous. The boundaries of the variation effect were assessed in Experiment II. In addition to the simple-complex variation of the relevant attributes, the values of the irrelevant attributes either varied across trials in the diverse groups or remained constant in the constant groups. One-adjective messages were informative only in the simple-constant group; in the other groups, such messages were predominantly ambiguous. Thus, young children can base their communications on a comparative analysis of stimulus arrays, but performance deteriorates when there is any variation in relevant or irrelevant attributes. These results were discussed in relation to various theories of the development of meaning and communication: the cognitive overload theory, the broad context theory, and the perceptual saliency theory.     

An Exploration of Trainees’ Perception of Clinical Psychology Training in India: A Qualitative Analysis

This study explored trainees’ perception of clinical psychology training in India. A sample of 20 (18 females; 2 males; Mean age?=?25 years) clinical psychology trainees participated in the study following written informed consent. Participants were interviewed individually (40–50 min) using a semi-structured interview schedule developed for the study. Interviews were audio recorded and transcribed. Broader themes were identified using principles of content analysis. The findings indicated trainees’ great enthusiasm about practical training, supervisor supervision and hospital based training. Results also showed poor recognition of the role of research and theory in training, unilateral view of supervision, poor perception of secondary goals and components of training and limited awareness about variety of clinical material. The results are indicative of trainees’ preference of clinical component of training over theory and research components of training, the backbone of prevailing systems of training globally. The preliminary findings suggest the need for further research in this area.     

Therapeutic Identity among Clinical Psychology Professionals in India

This study explored the therapeutic identity among clinical psychology professionals in India with objectives of assessing therapeutic style, attitudes, orientation, values and its relationship with work experience, age and gender. Out of 79 clinical psychology professionals contacted, 50 gave written informed consent for participation in study. The data obtained from Psycho-Therapeutic Identity Questionnaire (ThIdQ). Cluster analysis of the responses on attitude scales revealed broad themes of therapeutic identity in the form of three cluster profiles: Vague psychodynamic assumptions with high self-doubt and low optimism about change (n = 9); Entangled in their own strong feelings of limitations and doubts as a therapist (n = 16); and Eclectic approach with low self-doubt and high optimism about change(n = 25). A lack of synchrony was seen between assessed and reported therapeutic orientation with overuse of the cognitive behavioural therapy (CBT) orientation. Correlation findings indicated that increased work experience in the field and higher age were associated with low self-doubt and high optimism about change in therapy. Findings on therapeutic identity provide mixed bag of results, positive as well as negative, with equal number of participants on each side.     

Examining Cultural,Ethnic, and Religious Differences with the Brief Multidimensional Measure of Religiousness and Spirituality in the U.S. and India

Journal of Religion and Health - The Brief Multidimensional Measure of Religiousness/Spirituality (BMMRS) is regularly used to measure spirituality and religiosity in U.S. Christian populations,...