What information is necessary for speech categorization? Harnessing variability in the speech signal by integrating cues computed relative to expectations

Most theories of categorization emphasize how continuous perceptual information is mapped to categories. However, equally important are the informational assumptions of a model, the type of information subserving this mapping. This is crucial in speech perception where the signal is variable and context dependent. This study assessed the informational assumptions of several models of speech categorization, in particular, the number of cues that are the basis of categorization and whether these cues represent the input veridically or have undergone compensation. We collected a corpus of 2,880 fricative productions (Jongman, Wayland, & Wong, 2000) spanning many talker and vowel contexts and measured 24 cues for each. A subset was also presented to listeners in an 8AFC phoneme categorization task. We then trained a common classification model based on logistic regression to categorize the fricative from the cue values and manipulated the information in the training set to contrast (a) models based on a small number of invariant cues, (b) models using all cues without compensation, and (c) models in which cues underwent compensation for contextual factors. Compensation was modeled by computing cues relative to expectations (C-CuRE), a new approach to compensation that preserves fine-grained detail in the signal. Only the compensation model achieved a similar accuracy to listeners and showed the same effects of context. Thus, even simple categorization metrics can overcome the variability in speech when sufficient information is available and compensation schemes like C-CuRE are employed.     

Mindlessness Revisited: Sequential Request Techniques Foster Compliance by Draining Self-control Resources

The present research extends previous findings suggesting that sequential request techniques, such as the Foot-in-the-Door (FITD) or Door-in-the-Face (DITF) technique, are primarily effective under conditions conducive of mindlessness. We forward that this mindlessness may be the product of the influence technique itself. More specifically, based on the notion of self-control as a limited resource, we hypothesize that actively responding to the initial request-phase of a FITD-compliance gaining procedure drains the target of his/her self-regulatory resources, thus creating the mindlessness so often observed in social influence settings. This resource depletion opens the door for compliance with the target request. The results were in line with these expectations. More specifically, we observed that active responding to an initial request of a FITD technique reduced the availability of self-regulatory resources. This state of resource depletion mediated the effect of the technique on behavioral compliance. In addition, the results of this study ruled out the alternate explanation that the effects were attributable to mood or a general tendency for acquiescence.     

Continuous dynamics of color categorization

In order to assess whether color categorization is sensitive to within-category differences in hue, we monitored mouse trajectories in a modified categorization task. Participants saw color swatches from a blue-green continuum and categorized them with a computer mouse by selecting one of two colored regions at the top of a monitor. An analysis of the mouse trajectories showed that the deviation toward the competing category was a function of hue: As hues approached the category boundary, they increasingly deviated to the competitor. This work presents evidence for parallel activation on the level of hue and category processing for color, as well as simultaneous activation of perceptually adjacent categories. Thus, a dynamic process sensitive to fine-grained within-category detail best characterizes color categorization.     

Weber-Fechner behavior in symmetry perception?

The literature contains several allusions to the idea that detection of (mirror) symmetry in the presence of noise follows the Weber-Fechner law. This law usually applies to first-order structures, such as length, weight, or pitch, and it holds that just-noticeable differences in a signal vary in proportion to the strength of the signal. Symmetry, however, is a higher order structure, and this theoretical note starts from the idea that, in noisy symmetry, the regularity-to-noise ratio defines the strength of the signal to be considered. We argue that the detectability of the symmetry follows a psychophysical law that also holds for Glass patterns. This law deviates from the Weber-Fechner law in that it implies that, in the middle range of noise proportions, the sensitivity to variations in the regularity-to-noise ratio is disproportionally higher than in both outer ranges.     

Cue integration with categories: Weighting acoustic cues in speech using unsupervised learning and distributional statistics

During speech perception, listeners make judgments about the phonological category of sounds by taking advantage of multiple acoustic cues for each phonological contrast. Perceptual experiments have shown that listeners weight these cues differently. How do listeners weight and combine acoustic cues to arrive at an overall estimate of the category for a speech sound? Here, we present several simulations using a mixture of Gaussians models that learn cue weights and combine cues on the basis of their distributional statistics. We show that a cue‐weighting metric in which cues receive weight as a function of their reliability at distinguishing phonological categories provides a good fit to the perceptual data obtained from human listeners, but only when these weights emerge through the dynamics of learning. These results suggest that cue weights can be readily extracted from the speech signal through unsupervised learning processes.     

The End(s) of Philosophy: Rhetoric, Therapy and Wittgenstein's Pyrrhonism

In Culture and Value Wittgenstein remarks: ‘Thoughts that are at peace. That's what someone who philosophizes yearns for’. The desire for such conceptual tranquillity is a recurrent theme in Wittgenstein's work, and especially in his later ‘grammatical‐therapeutic’ philosophy. Some commentators (notably Rush Rhees and C. G. Luckhardt) have cautioned that emphasising this facet of Wittgenstein's work ‘trivialises’ philosophy – something which is at odds with Wittgenstein's own philosophical ‘seriousness’ (in particular his insistence that philosophy demands that one ‘Go the bloody hard way’). Drawing on a number of correlations between Wittgenstein's conception of philosophy and that of the Pyrrhonian Sceptics, in this paper I defend a strong ‘therapeutic’ reading of Wittgenstein, and show how this can be maintained without ‘trivialising’ philosophy.     

Concurrent Validity of the Schwartz Outcome Scale With a Chemically Dependent Population

Clients (N = 151) completed the Schwartz Outcome Scale (SOS‐10; M. A. Blais et al., 1999) and the Substance Abuse Subtle Screening Inventory‐3 (F. G. Miller & L. E. Lazowski, 1999). The results show a negative relationship between substance use symptoms and SOS‐10 scores and a positive relationship between defensiveness and SOS‐10 scores.     

Human variable ratio performance

The generality of the mathematical principles of reinforcement (MPR) was tested with humans. In Experiment 1A, participants’ mouse clicks were reinforced according to a series of variable-ratio (VR) values. In one condition, a situated task was used (searching for treasure on a map presented via a PC monitor); in the other, abstract version of the task, participants clicked on a white screen. Under the “map” condition, response rates increased with increasing ratio value before decreasing with further ratio increases; under the “no-map” condition, response rates decreased linearly from a peak at the smallest ratio. In Experiment 1B, the pattern of responding was confirmed under the “map” conditions using a different set of ratio values. In Experiment 2, reinforcer magnitude was manipulated using the “map” context. Response rates did not differ significantly when large rather than small cash reinforcers were delivered according to a VR 30 but were significantly higher when large rather than small cash reinforcers were delivered according to a VR 120. Together these experiments offer qualified support for extending MPR to the behavior of human participants.