Staying Together: A Bidirectional Delay–Coupled Approach to Joint Action

To understand how individuals adapt to and anticipate each other in joint tasks, we employ a bidirectional delay–coupled dynamical system that allows for mutual adaptation and anticipation. In delay–coupled systems, anticipation is achieved when one system compares its own time‐delayed behavior, which implicitly includes past information about the other system’s behavior, with the other system’s instantaneous behavior. Applied to joint music performance, the model allows each system to adapt its behavior to the dynamics of the other. Model predictions of asynchrony between two simultaneously produced musical voices were compared with duet pianists’ behavior; each partner performed one voice while auditory feedback perturbations occurred at unpredictable times during live performance. As the model predicted, when auditory feedback from one musical voice was removed, the asynchrony changed: The pianist’s voice that was removed anticipated (preceded) the actions of their partner. When the auditory feedback returned and both musicians could hear each other, they rapidly returned to baseline levels of asynchrony. To understand how the pianists anticipated each other, their performances were fitted by the model to examine change in model parameters (coupling strength, time‐delay). When auditory feedback for one or both voices was removed, the fits showed the expected decrease in coupling strength and time‐delay between the systems. When feedback about the voice(s) returned, the coupling strength and time‐delay returned to baseline. These findings support the idea that when people perform actions together, they do so as a coupled bidirectional anticipatory system.     

Children's perception of certain musical properties: scale and contour

Children's perception of scale and contour in melodies was investigated in five studies. Experimental tasks included judging transposed renditions of melodies (Studies 1 and 3), discriminating between transposed renditions of a melody (Study 2), judging contour-preserving transformations of melodies (Study 4), and judging similarity to a familiar target melody of transformations preserving rhythm or rhythm and contour (Study 5). The first and second studies showed that young children detect key transposition changes even in familiar melodies and they perceive similarity over key transpositions even in unfamiliar melodies. Young children also are sensitive to melodic contour over transformations that preserve it (Study 5), yet they distinguish spontaneously between melodies with the same contour and different intervals (Study 4). The key distance effect reported in the literature did not occur in the tasks of this investigation (Studies 1 and 3), and it may be apparent only for melodies shorter or more impoverished than those used here.     

How internal can you get?

This paper examines Laurence BonJour's defense of internalism inThe Structure of Empirical Knowledge with an eye toward better understanding the issues which separate internalists from externalists. It is argued that BonJour's Doxastic Presumption cannot play the role which is required of it to make his internalism work. It is further argued that BonJour's internalism, and, indeed, all other internalisms, are motivated by a Cartesian view of an agent's access to her own mental states. This Caretsian view is argued to be untenable, and, accordingly, so is internalism.     

Analysis of periodic data using Walsh functions

Data often contain periodic components plus random variability. Walsh analysis reveals periodicities by fitting rectangular functions to data. It is analogous to Fourier analysis, which represents data as sine and cosine functions. For many behavioral measures, Fourier transforms can produce spurious peaks in power spectra and fail to resolve separable components. Walsh analysis is superior for strongly discontinuous data. The strengths and weaknesses of each transform are discussed, and specific algorithms are given for the newer Walsh technique.     

Sensible reasoning in two tasks: Rule discovery and hypothesis evaluation

The hypothesis testing skills of undergraduates were measured in two tasks: the 2-4-6 rule discovery task in which students generate and assess hypotheses, and a hypothesis evaluation task, which requires only the assessment of hypotheses. The results of Experiments 1 and 2 show that the students consistently employed a disconfirmation strategy when assessing hypotheses, but employed a counterfactual inference strategy when they also were required to generate the hypotheses. The results of Experiment 3 suggest that the selection of the hypothesis testing strategy reflected a balance between the logical requirements of the task and the desirability of possible outcomes. Taken together, the findings support a more consistent picture of human rationality across tasks, and suggest alternatives to accounts of confirmation bias.     

Separability and integrality of global and local levels of hierarchical patterns

We used a constrained classification task to examine the perceptual relations between global and local levels in hierarchical patterns composed of many, relatively small elements and those composed of few, relatively large elements. In Experiments 1 and 3 subjects were asked to make classifications based on "form" or "texture." In Experiments 2 and 4 they were asked to classify according to the "shape" of the configuration or the elements. The results indicate that configural and elemental levels are perceptually separable for many-element patterns when processed as form and texture: Subjects could attend to either level without being affected by variation along the irrelevant dimension. However, when the same many-element patterns were processed for global and local shape, subjects could not selectively attend to either level. For few-element patterns, global configuration and local elements appeared to be perceptually integral dimensions. These results are relevant to two issues: the global precedence hypothesis and the explanations of integral and separable dimensions.