The development of voicing categories: A quantitative review of over 40 years of infant speech perception research

Most research on infant speech categories has relied on measures of discrimination. Such work often employs categorical perception as a linking hypothesis to enable inferences about categorization on the basis of discrimination measures. However, a large number of studies with adults challenge the utility of categorical perception in describing adult speech perception, and this in turn calls into question how to interpret measures of infant speech discrimination. We propose here a parallel channels model of discrimination (built on Pisoni and Tash Perception & Psychophysics, 15(2), 285–290, 1974), which posits that both a noncategorical or veridical encoding of speech cues and category representations can simultaneously contribute to discrimination. This can thus produce categorical perception effects without positing any warping of the acoustic signal, but it also reframes how we think about infant discrimination and development. We test this model by conducting a quantitative review of 20 studies examining infants’ discrimination of voice onset time contrasts. This review suggests that within-category discrimination is surprisingly prevalent even in classic studies and that, averaging across studies, discrimination is related to continuous acoustic distance. It also identifies several methodological factors that may mask our ability to see this. Finally, it suggests that infant discrimination may improve over development, contrary to commonly held notion of perceptual narrowing. These results are discussed in terms of theories of speech development that may require such continuous sensitivity.     

The development of causal categorization

Two experiments examined the impact of causal relations between features on categorization in 5- to 6-year-old children and adults. Participants learned artificial categories containing instances with causally related features and noncausal features. They then selected the most likely category member from a series of novel test pairs. Classification patterns and logistic regression were used to diagnose the presence of independent effects of causal coherence, causal status, and relational centrality. Adult classification was driven primarily by coherence when causal links were deterministic (Experiment 1) but showed additional influences of causal status when links were probabilistic (Experiment 2). Children's classification was based primarily on causal coherence in both cases. There was no effect of relational centrality in either age group. These results suggest that the generative model (Rehder, 2003a) provides a good account of causal categorization in children as well as adults.     

Can attentional control settings be maintained for two color–location conjunctions? Evidence from an RSVP task

Previous investigations of the ability to maintain separate attentional control settings for different spatial locations have relied principally on a go/no-go spatial-cueing paradigm. The results have suggested that control of attention is accomplished only late in processing. However, the go/no-go task does not provide strong incentives to withhold attention from irrelevant color–location conjunctions. We used a modified version of the task in which failing to adopt multiple control settings would be detrimental to performance. Two RSVP streams of colored letters appeared to the left and right of fixation. Participants searched for targets that were a conjunction of color and location, so that the target color for one stream acted as a distractor when presented in the opposite stream. Distractors that did not match the target conjunctions nevertheless captured attention and interfered with performance. This was the case even when the target conjunctions were previewed early in the trial prior to the target (Exp. 2). However, distractor interference was reduced when the upcoming distractor was previewed early on in the trial (Exp. 3). Attentional selection of targets by color–location conjunctions may be effective if facilitative attentional sets are accompanied by the top-down inhibition of irrelevant items.     

The effects of context change on long-term habituation of the orienting response in humans

Four experiments examined the effects of context change (Experiments 1-3) and context extinction (Experiment 4) on long-term habituation of the skin conductance response. In all experiments, subjects received 15 presentations of a target stimulus in each of two sessions. In Experiment 1 (N=60) there was a 15-min interval between training and test sessions. This interval was extended to 24 hours in Experiments 2 (N=60) and 3 (N=60). The experimental treatment in each of these studies involved a change in context between the two training sessions. None of the experiments provided evidence of context dependency in measures of long-term habituation. In Experiment 4 (N=60) experimental subjects received a period of context extinction during which they remained in the laboratory environment between two series of habituation trials. Again, however, there was no evidence that long-term habituation was contextually mediated. Thus, the results fail uniformly to support theories that argue that long-term habituation is context-dependent.     

Facsimiles of Flesh

Ed Gein was a serial killer, grave robber, and body snatcher who made a lampshade from human skin. Now consider the detective who found that lampshade. Let's suppose that he would never want to own it; however, he does find that he wants a synthetic one just like it – a perfect replica. We assume that there is something morally problematic about the detective having such a replica. We then argue that, given as much, we can reach the surprising conclusion that it's morally problematic to consume realistic fake‐meat products. After explaining why we might the detective's replica lampshade morally problematic, we clarify the analogy between the replica and fake meat products. Then, we defend it against a number of objections, the most notable one being we can sever any association between fake meat and the real stuff without moral cost. We conclude by pointing out that our argument generalises: if it works, then there is something morally problematic about many fake animal products, including fake leather and fur.     

Traumatic stress, dissociation, and limbic irritability in patients with unipolar depression being treated with SSRIs

Recent evidence suggests that stressful experiences may be related to deficits in inhibitory functions and temporo-limbic epileptic-like activity. The latter may produce psychosensory seizure-like symptoms that may also appear in nonepileptic conditions. This study assesses whether the increased presence of the seizure-like symptoms in 113 unipolar depressive patients treated with SSRIs is associated with significantly more severe symptoms of depression, traumatic stress, and dissociation in comparison with 86 healthy controls. Results indicate that seizure-like symptoms in depressive patients have significant association with depression, symptoms of dissociation, and traumatic stress. This association suggests that processess generating seizure-like symptoms may be related to symptoms of depression, traumatic stress, and dissociation.     

The emotional feeling as a combination of two qualia: A neurophilosophical-based emotion theory

It is argued that the emotional feeling comprises the following two emotional qualia. (1) A nucleus feeling or primary emotional quale, which is the phenomenological counterpart of the end product of appraisal by the central nervous system. (2) The experience of being urged to emotion-related reflection or secondary emotional quale, which is the phenomenological counterpart of the brain's decision to inhibit pre-programmed emotional behaviour, and to initiate emotion-related reflections. Different brain modules regulate these two qualia, and thus each can be experienced independently of the other. The primary emotional quale is related to activation of the amygdala, it is emotion specific, and neutral with respect to affect. The secondary emotional quale is related to activation of the orbito-prefrontal cortex (O-PFC), and includes affective aspects.

It is argued that emotional behaviour is regulated by the following three neural mechanisms, two of which two are directly related to the two qualia. (1) An evolutionary ancient system (amygdala-system), which comprises the amygdalae and subcortical nuclei, and which activates pre-programmed emotional behaviour. (2) An evolutionary recent system (PFC-system), comprising the prefrontal cortex, which inhibits pre-programmed emotional behaviour, activates emotional reflection, generates and evaluates behavioural alternatives. In contrast to the pre-programmed behaviour, the behavioural alternatives are more likely to serve long-term goals. (3) A default mechanism, which gives rise to default (i.e., “just do something”) behaviour. The first two systems are mutually competitive, while the third mechanism takes over if either the competition between the first two mechanisms, or the decision process of the PFC-system, takes too long. This default mechanism involves the function of the medial-prefrontal cortex (M-PFC).