On the interplay of temporal resolution power and spatial suppression in their prediction of psychometric intelligence.

As a measure of the brain's temporal fine-tuning capacity, temporal resolution power (TRP) explained repeatedly a substantial amount of variance in psychometric intelligence. Recently, spatial suppression, referred to as the increasing difficulty in quickly perceiving motion direction as the size of the moving stimulus increases, has attracted particular attention, when it was found to be positively related to psychometric intelligence. Due to the conceptual similarities of TRP and spatial suppression, the present study investigated their mutual interplay in the relation to psychometric intelligence in 273 young adults to better understand the reasons for these relationships. As in previous studies, psychometric intelligence was positively related to a latent variable representing TRP but, in contrast to previous reports, negatively to latent and manifest measures of spatial suppression. In a combined structural equation model, TRP still explained a substantial amount of variance in psychometric intelligence while the negative relation between spatial suppression and intelligence was completely explained by TRP. Thus, our findings confirmed TRP to be a robust predictor of psychometric intelligence but challenged the assumption of spatial suppression as a representation of general information processing efficiency as reflected in psychometric intelligence. Possible reasons for the contradictory findings on the relation between spatial suppression and psychometric intelligence are discussed

Do executive attentional processes uniquely or commonly explain psychometric g and correlations in the positive manifold? A structural equation modeling and network-analysis approach to investigate the Process Overlap Theory

One of the best-established findings in intelligence research is the pattern of positive correlations among various intelligence tests. Although this so-called positive manifold became the conceptual foundation of many theoretical accounts of intelligence, the very nature of it has remained unclear. Only recently, Process Overlap Theory (POT) proposed that the positive manifold originated from overlapping domain-general, executive processes. To test this assumption, the functional relationship between different aspects of executive attention and the positive manifold was investigated by re-analyzing an existing dataset (N = 228). Psychometric reasoning, speed, and memory performance were assessed by a short form of the Berlin Intelligence Structure test. Two aspects of executive attention (sustained and selective attention) and speed of decision making were measured by a continuous performance test, a flanker task, and a Hick task, respectively. Traditional structural equation modeling, representing the positive manifold by a g factor, as well as network analyses, investigating the differential effects of the two aspects of executive attention and speed of decision making on the specific correlations of the positive manifold, suggested that selective attention, sustained attention, and speed of decision making explained the common but not the unique portions of the positive manifold. Thus, we failed to provide evidence for POT’s assumption that the positive manifold is the result of overlapping domain-general processes. This does not mean that domain-general processes other than those investigated here will not be able to show the pattern of results predicted by POT

Relations among fluid intelligence, sensory discrimination and working memory in middle to late childhood – A latent variable approach

Two factors that have been suggested as key in explaining individual differences in fluid intelligence are working memory and sensory discrimination ability. A latent variable approach was used to explore the relative contributions of these two variables to individual differences in fluid intelligence in middle to late childhood. A sample of 263 children aged 7–12 years was examined. Correlational analyses showed that general discrimination ability (GDA)and working memory (WM) were related to each other and to fluid intelligence. Structural equation modeling showed that within both younger and older age groups and the sample as a whole, the relation between GDA and fluid intelligence could be accounted for by WM. While WM was able to predict variance in fluid intelligence above and beyond GDA, GDA was not able to explain significant amounts of variance in fluid intelligence, either in the whole sample or within the younger or older age group. We concluded that compared to GDA, WM should be considered the better predictor of individual differences in fluid intelligence in childhood. WM and fluid intelligence, while not being separable in middle childhood, develop at different rates, becoming more separable with age

Developing a Psychophysical Measure to Assess Duration Discrimination in the Millisecond Range

Duration discrimination in the range of milliseconds is essential for various aspects of behavior and individual differences. The present paper addresses important methodological issues, such as type of stimuli, type of task, method for threshold estimation, and temporal sensitivity of the psychophysical procedure, that should be borne in mind when developing a sensitive and reliable duration discrimination task. Furthermore, it introduces a psychophysical approach for the assessment of individual differences in duration discrimination of extremely brief intervals in the subsecond range. Monte Carlo simulations provide clear evidence that this task is sensitive enough to correctly detect a true difference between temporal stimuli as small as 2 ms with a high probability. Further, the distributional properties of individual performance scores obtained from 534 participants by means of the introduced duration discrimination task are presented. </jats:p

The relationship between attentional blink and psychometric intelligence: A fixed-links model approach

Attentional blink (AB) denotes the impairment in identifying a target when this target follows a preceding target after about 150 to 500 msec. Several models explain AB and some studies suggest that more processes than only one are involved in AB. Therefore, confounding effects of these underlying processes might be the reason why previous studies could not observe a relationship between AB and psychometric intelligence. In the present study, fixed-links models were used to disentangle the processes underlying the performance of 66 female and 52 male volunteers on an AB task. In accordance with theoretical explanations of AB, three latent variables with loadings describing a linearly increasing, a linearly decreasing and a u-shaped trend described the data well. Psychometric intelligence was related to the latent variables reflected by the u-shaped (β = .30; p < .05) and the linearly increasing trends (β = .23; p < .05) but not to the latent variable reflected by the linearly decreasing trend (β = .10; n.s.). These results support the assumptions that more processes than only one are involved in AB. Decomposition of the underlying processes seems to be promising to investigate intelligence-related individual differences on this early level of information processing

Evidence for different processes involved in the effects of nontemporal stimulus size and numerical digit value on duration judgments

Perceived duration has been shown to be positively related to task-irrelevant, nontemporal stimulus magnitude. To account for this finding, Walsh's (2003) A Theory of Magnitude (ATOM) model suggests that magnitude of time is not differentiated from magnitude of other nontemporal stimulus characteristics and collectively processed by a generalized magnitude system. In Experiment 1, we investigated the combined effects of stimulus size and numerical quantity, as two nontemporal stimulus dimensions covered by the ATOM model, on duration judgments. Participants were required to reproduce the duration of target intervals marked by Arabic digits varying in physical size and numerical value. While the effect of stimulus size was effectively moderated by target duration, the effect of numerical value appeared to require attentional resources directed to the numerical value in order to become effective. Experiment 2 was designed to further elucidate the mediating influence of attention on the effect of numerical value on duration judgments. An effect of numerical value was only observed when participants' attention was directed to digit value, but not when participants were required to pay special attention to digit parity. While the ATOM model implies a common metrics and generalized magnitude processing for time, size, and quantity, the present findings provided converging evidence for the notion of two qualitatively different mechanisms underlying the effects of nontemporal stimulus size and numerical value on duration judgments. Furthermore, our data challenge the implicit common assumption that the effect of numerical value on duration judgments represents a continuously increasing function of digit magnitude