An fMRI investigation on image generation in different sensory modalities: The influence of vividness

In the present fMRI study the issue of the specific cortices activation during imagery generation in different sensory modalities is addressed. In particular, we tested whether the vividness variability of imagery was reflected in the BOLD signal within specific sensory cortices. Subjects were asked to generate a mental image for each auditory presented sentence. Each imagery modality was contrasted with an abstract sentence condition. In addition, subjects were asked to fill the Italian version of the Questionnaire Upon Mental Imagery (QMI) prior to each neuroimaging session. In general, greater involvement of sensory specific cortices in high-vivid versus low-vivid subjects was found for visual (occipital), gustatory (anterior insula), kinaesthetic (pre-motor), and tactile and for somatic (post-central parietal) imagery modalities. These results support the hypothesis that vividness is related to image format: high-vivid subjects would create more analogical representations relying on the same specific neural substrates active during perception with respect to low-vivid subjects. Results are also discussed according to the simulation perspective.     

Extended Life

This paper reformulates some of the questions raised by extended mind theorists from an enactive, life/mind continuity perspective. Because of its reliance on concepts such as autopoiesis, the enactive approach has been deemed internalist and thus incompatible with the extended mind hypothesis. This paper answers this criticism by showing (1) that the relation between organism and cogniser is not one of co-extension, (2) that cognition is a relational phenomenon and thereby has no location, and (3) that the individuality of a cogniser is inevitably linked with the question of its autonomy, a question ignored by the extended mind hypothesis but for which the enactive approach proposes a precise, operational, albeit non-functionalist answer. The paper raises a pespective of embedded and intersecting forms of autonomous identity generation, some of which correspond to the canonical cases discussed in the extended mind literature, but on the whole of wider generality. In addressing these issues, this paper proposes unbiased, non-species specific definitions of cognition, agency and mediation, thus filling in gaps in the extended mind debates that have led to paradoxical situations and a problematic over-reliance on intutions about what counts as cognitive.

Variables and Quantity: What Else?

The article aims to comment Toomela’s (Integrative Psychological & Behavioral Science 42(3):245–265, 2008) paper on variables and quantitative psychology. Topics as the choice of variables, their measurement and statistical analysis, the deductions based on data, are briefly reviewed. All variables can be misleading if used in a misleading way, but the Author contends that the psychology based on the variables has not the possibility to represent selected samples of inner processes and contents. Quantitative analyses based on linear causality and probabilistic inference pose many problems, but some alternative approaches devised to cope with these problems are indicated. An hermeneutic approach aware of the constructivist ground of the scientific knowledge is proposed.

The attentional blink with targets in different spatial locations

When two targets (T1 and T2) are displayed in rapid succession, accuracy of T2 identification varies as a function of the temporal lag between the targets (attentional blink, AB). In some studies, performance has been found to be most impaired at Lag 1—namely, when T2 followed T1 directly. In other studies, T2 performance at Lag 1 has been virtually unimpaired (Lag 1 sparing). In the present work, we examined how Lag 1 sparing is affected by attentional switches between targets displayed in the same location or in different locations. We found that Lag 1 sparing does not occur when a spatial shift is required between T1 and T2. This suggests that attention cannot be switched to a new location while the system is busy processing another stimulus. The results are explained by a modified version of an attentional gating model (Chun & Potter, 1995; Shapiro & Raymond, 1994).     

Effects of display luminance, stimulus meaningfulness, and probe duration on visible and schematic persistence

Partial report performance is conceived of as consisting of two independent sources of information: visible persistence and schematic persistence. Following the work of Di Lollo and Dixon (1988), these two sources of information were separated experimentally by varying interstimulus interval and stimulus onset asynchrony independently. In the present experiment we asked whether visible persistence and schematic persistence would be affected by display luminance, stimulus meaningfulness, or probe duration. The results were fit accurately by an extension of the Di Lollo and Dixon independent-decay model in which display luminance affected visible persistence but stimulus meaningfulness and probe duration affected neither form of persistence directly.     

Displacement limit (dmax) of sampled directional motion: direct and indirect estimates

The maximum displacement at which directional motion can be seen, known as dmax, has been said to define the spatial limits of the short-range motion system. Turano and Pantle (1985) used duration of motion aftereffect (MAE) to estimate the spatial limit of the short-range system, the assumption that dmax (a direct measure of motion perception) and MAE (an indirect measure) are equivalent indices of the same underlying perceptual process. In a series of four experiments, we examined this assumption by measuring dmax and duration of MAE across a range of displacements, stimulus waveforms (sine- or square-wave gratings), and spatial frequencies. We found that dmax and duration of MAE were affected differently by changes in the same variables. Therefore, we concluded that the two indices cannot be regarded as equivalent measures of the spatial limits of the short-range process. Two novel effects that separated MAE from motion detection are described, and suggestions for exploring them are outlined.     

Effects of modality preferences on learning and recall of bisensory stimuli

The performance of visual attenders and aural attenders, as defined by performance on a bisensory digit-span task, was compared on three bisensory tasks. First, in replication of an earlier study, performance was compared on a bisensory missing-unit paradigm, in which S was required to respond with missing units from two independent sets of stimuli, each set being presented on a separate channel. The results corroborated those of an earlier study in which an interaction between modality preferences and presentation modality was found. Further, differential recall patterns were found for each of the groups. While such comparable results were not found on the other two tasks, differential performance on a bisensory paired-associate task and a bisensory connected discourse task were found. The results are interpreted in accord with Murdock’s (1967) hypotheses concerning separate sensory storage mechanisms.