Chaos breeds autonomy: connectionist design between bias and baby-sitting

In connectionism and its offshoots, models acquire functionality through externally controlled learning schedules. This undermines the claim of these models to autonomy. Providing these models with intrinsic biases is not a solution, as it makes their function dependent on design assumptions. Between these two alternatives, there is room for approaches based on spontaneous self-organization. Structural reorganization in adaptation to spontaneous activity is a well-known phenomenon in neural development. It is proposed here as a way to prepare connectionist models for learning and enhance the autonomy of these models.     

Collinearity,curvature interpolation,and the power of perceptual integration

In three experiments, participants determined the orientation of a global triangle formed by three Gabor patches of a target spatial frequency in a field of distracters. The orientation of the target patches and their proximity were varied between conditions. When all the target patches had the same orientation this facilitated the response compared to random orientations. This effect occurred only when the patches were in close proximity. When the orientations of the target patches were different but aligned to the global triangle, facilitation occurred regardless of proximity. These contrasting types of facilitation were attributed to different early perceptual integration mechanisms that enable the perception of holistic structure.     

Visual marking and change detection

The preview benefit from prior exposure of response-irrelevant (distracter) objects in visual search has been accounted for in terms of top-down inhibition (i.e. visual marking), bottom-up abrupt onset capture, or asynchrony-dependent perceptual segregation. We assess the relative contribution of abrupt onset and visual marking in a paradigm combining visual search with a visual working memory task. We investigated time-based selection of multiple objects for storage in visual working memory, using a change detection paradigm (Luck and Vogel in Nature 390:279–281, 1997) with distracter preview. We varied preview exposure (short vs. long), in a series of three experiments. The contribution of asynchrony-related perceptual segregation was assessed across experiments by varying the complexity of the stimuli (colored squares, oriented bars and oriented T-shapes) and the type of change detection (color or orientation), resulting in different levels of perceptual segregation between visual elements. The results suggest that bottom-up abrupt onset, visual marking and perceptual segregation factors co-operate in time-based selection for storage in visual working memory.     

Bayesian estimation of a multilevel IRT model using gibbs sampling

In this article, a two-level regression model is imposed on the ability parameters in an item response theory (IRT) model. The advantage of using latent rather than observed scores as dependent variables of a multilevel model is that it offers the possibility of separating the influence of item difficulty and ability level and modeling response variation and measurement error. Another advantage is that, contrary to observed scores, latent scores are test-independent, which offers the possibility of using results from different tests in one analysis where the parameters of the IRT model and the multilevel model can be concurrently estimated. The two-parameter normal ogive model is used for the IRT measurement model. It will be shown that the parameters of the two-parameter normal ogive model and the multilevel model can be estimated in a Bayesian framework using Gibbs sampling. Examples using simulated and real data are given.     

The formal pace of Sesame Street over 26 years

Television producers often use a high rate in the succession of visual and auditory features in their programs to attract the attention of viewers. In this study an attempt was made to measure the formal pace of television programs by scoring the rates of an extensive set of formal visual and auditory characteristics. Sesame Street was chosen as a focal point because this educational program--with its high pace--is very successful in its competition with the majority of commercial programs from which children can choose to watch at home. The analyzed material consisted of 49 Dutch episodes of Sesame Street broadcast between 1977 and 2003. The formal pace characteristics of separate program items from Sesame Street could be reliably established. Factor analysis indicated that clear pace factors were (a) "editing," consisting of a frequent use of different types of shots (total shots, medium shots, and close-ups) combined with a large number of cuts and (b) speech rate. Over a period of 26 years, the pace of editing increased: the mean number of cuts increased from about 4 to 8 per minute. The mean speech rate decreased from 175 to 139 words per minute.     

Amodal completion as reflected by gaze durations

In two experiments amodal completion of partly occluded shapes was investigated by recording eye movements in a directed visual-search task. Participants searched arrays of shapes in a prescribed order for target figures that could partly be occluded. Longer gaze durations were found on occlusion patterns than on truncated control patterns for targets but not for non-targets. This effect of occlusion was restricted to a subset of the stimuli. A second experiment was carried out to establish whether this restriction resulted from structural properties of the stimuli or their familiarity. Occlusion patterns in this experiment were ambiguous with respect to structure, allowing both local and global completions. One of the completions was always less familiar than the other. The results showed longer gazes only for the less familiar completions, irrespective of whether they were local or global.     

Negative congruence effects in letter and pseudo-letter recognition: the role of similarity and response conflict

Letters and pseudo-letters were presented in three experiments using a sequential same-different task. While first items were always presented in isolation, the second item was either presented in isolation or surrounded by geometrical non-target shapes that could be congruent or incongruent to the target. In two experiments, a physical sameness criterion was used. In Experiment 1, in one condition, different pairs were always distinct in shape, in another they were similar in shape. Negative congruence effects were obtained for different pairs that are similar. In Experiment 2, this effect is replicated within participants. In this experiment, similar and dissimilar stimuli were mixed. The results were explained in terms of the difficulty of responding different to stimuli that are similar in shape: when the second item is surrounded by a congruent shape, the similarity is emphasized, making this response even more difficult. In Experiment 3, the same stimuli were presented using a categorical sameness criterion. This reduces the role of physical similarity and thus eliminates the response conflict. As a result, negative congruence effects were no longer observed. Taken together, the three experiments identify another source of negative congruence effects besides the ones recently reported in the literature.     

Behavioural treatment of trichotillomania: two-year follow-up results

Post-treatment evaluation studies of behaviour therapy (BT) for trichotillomania (TTM) have shown that BT is successful in reducing symptoms in this impulse-control disorder. The present study was aimed at investigating gain maintenance at long-term follow-up. TTM-related symptoms and other symptom characteristics were evaluated in 28 patients suffering from TTM before and after brief BT and at a 3-month and 2-year follow-up. The manual-based BT consisted of self-control procedures offered in six sessions. Pre-post effect sizes for TTM symptoms at post-treatment evaluation and at the two follow-ups were 2.91, 1.47, and .87. Compared to the post-treatment effects, the 3-month and 2-year follow-up effect sizes had decreased by 49% and 70%, respectively. Better 2-year follow-up results were associated with lower pre-treatment levels of depressive symptoms and with complete abstinence from hair pulling immediately after treatment.     

Perceptual switching,eye movements,and the bus paradox

According to a widely cited finding by Ellis and Stark (1978 Perception 7 575-581), the duration of eye fixations is longer at the instant of perceptual reversal of an ambiguous figure than before or after the reversal. However, long fixations are more likely to include samples of an independent random event than are short fixations. This sampling bias would produce the pattern of results also when no correlation exists between fixation duration and perceptual reversals. When an appropriate correction is applied to the measurement of fixation durations, the effect disappears. In fact, there are fewer actual button-presses during the long intervals than would be expected by chance. Moving-window analyses performed on eye-fixation data reveal that no unique eye event is associated with switching behaviour. However, several indicators, such as blink frequency, saccade frequency, and the direction of the saccade, are each differentially sensitive to perceptual and response-related aspects of the switching process. The time course of these indicators depicts switching behaviour as a process of cascaded stages.     

SNARC (spatial–numerical association of response codes) meets SPARC (spatial–pitch association of response codes): Automaticity and interdependency in compatibility effects

Concepts, including the mental number line, or addressing pitch as high and low, suggest that the spatial–numerical and spatial–pitch association of response codes (SNARC and SPARC) effects are domain-specific and thus independent. Alternatively, there may be dependencies between these effects, because they share common automatic or controlled decision mechanisms. In two experiments, participants were presented with spoken numbers in different pitches; their numerical value, pitch, and response compatibility were varied systematically. This allowed us to study SNARC and SPARC effects in a factorial design (see also Fischer, Riello, Giordano, &; Rusconi, 2013 Fischer, M. H., Riello, M., Giordano, B. L., &; Rusconi, E. (2013). Singing numbers?…?in cognitive space--a dual-task study of the link between pitch, space, and numbers. Topics in Cognitive Science, 5(2), 354–366. Retrieved from http://doi.org/10.1111/tops.12017[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Participants judged the stimuli on numerical magnitude, pitch, or parity (odd–even). In all tasks, the SNARC and SPARC effects had superadditive interactions. These were interpreted as both effects sharing a common mechanism. The task variation probes the mechanism: In the magnitude judgement task, numerical magnitude was explicit, whereas pitch was implicit; in the pitch judgement task, it was vice versa. In the parity judgement task, both dimensions were implicit. Regardless of whether they were implicit or explicit, both SNARC and SPARC effects occurred in all tasks. We concluded that by not requiring focal attention the common mechanism operates automatically.