Conceptual complexity and the bias/variance tradeoff

In this paper we propose that the conventional dichotomy between exemplar-based and prototype-based models of concept learning is helpfully viewed as an instance of what is known in the statistical learning literature as the bias/variance tradeoff. The bias/variance tradeoff can be thought of as a sliding scale that modulates how closely any learning procedure adheres to its training data. At one end of the scale (high variance), models can entertain very complex hypotheses, allowing them to fit a wide variety of data very closely—but as a result can generalize poorly, a phenomenon called overfitting. At the other end of the scale (high bias), models make relatively simple and inflexible assumptions, and as a result may fit the data poorly, called underfitting. Exemplar and prototype models of category formation are at opposite ends of this scale: prototype models are highly biased, in that they assume a simple, standard conceptual form (the prototype), while exemplar models have very little bias but high variance, allowing them to fit virtually any combination of training data. We investigated human learners’ position on this spectrum by confronting them with category structures at variable levels of intrinsic complexity, ranging from simple prototype-like categories to much more complex multimodal ones. The results show that human learners adopt an intermediate point on the bias/variance continuum, inconsistent with either of the poles occupied by most conventional approaches. We present a simple model that adjusts (regularizes) the complexity of its hypotheses in order to suit the training data, which fits the experimental data better than representative exemplar and prototype models.     

Superordinate shape classification using natural shape statistics

This paper investigates the classification of shapes into broad natural categories such as animal or leaf. We asked whether such coarse classifications can be achieved by a simple statistical classification of the shape skeleton. We surveyed databases of natural shapes, extracting shape skeletons and tabulating their parameters within each class, seeking shape statistics that effectively discriminated the classes. We conducted two experiments in which human subjects were asked to classify novel shapes into the same natural classes. We compared subjects’ classifications to those of a naive Bayesian classifier based on the natural shape statistics, and found good agreement. We conclude that human superordinate shape classifications can be well understood as involving a simple statistical classification of the shape skeleton that has been “tuned” to the natural statistics of shape.     

Influencing Republicans’ and Democrats’ attitudes toward Obamacare: Effects of imagined vicarious cognitive dissonance on political attitudes

The field of experimental social psychology is appropriately interested in using novel theoretical approaches to implement change in the social world. In the current study, we extended cognitive dissonance theory by creating a new framework of social influence: imagined vicarious dissonance. We used the framework to influence attitudes on an important and controversial political attitude: U.S. citizens’ support for the Affordable Care Act (ACA). 36 Republicans and 84 Democrats were asked to imagine fellow Republicans and Democrats, respectively, making attitude discrepant statements under high and low choice conditions about support for the ACA. The data showed that vicarious dissonance, established by imagining a group member make a counterattitudinal speech under high-choice conditions (as compared to low-choice conditions), resulted in greater support for the Act by Republicans and marginally diminished support by Democrats. The results suggest a promising role for the application of vicarious dissonance theory to relevant societal issues and for further understanding the relationship of dissonance and people’s identification with their social groups.     

The Role of Religious Beliefs in Coping With Chronic Illness

The authors examined the ways in which 40 women with chronic illnesses (rheumatoid arthritis, osteoporosis, multiple sclerosis, systemic lupus erythematosus, or a combination of these disorders) used religious beliefs as a means of coping with their illnesses, The participants, all between the ages of 28 and 79 years, were interviewed about the role religious beliefs played in their experiences and the ways in which they made meaning in their lives or coped with their illnesses. The majority of the women reported that religious beliefs were important in living with a chronic illness. In addition, more women who were identified as coping well with their illness reported strong religious beliefs, whereas the majority of women identified as poor copers reported that religion was unimportant or that they had no religious beliefs.     

Typing Problems

Guided by the work of William Alston, Jonathan Adler and Michael Levin propose a solution to the generality problem for reliabilism. In some respects their proposal improves on those we have discussed. We argue that the problem remains unsolved.     

Collateral effects of behavioral parent training on families of children with developmental disabilities and behavior disorders

We evaluated collateral effects of behavioral parent training (BPT) on families with children who have developmental disabilities and behavior disorders. We compared 18 BPT graduates to 18 similar families waiting for service. The BPT graduates reported significantly less (i) child behavior problems, (ii) disruption to child and family quality of life due to child problem behavior, and (iii) stress related to limits on family opportunities and child physical limitations, up to 5 years after discharge. On a self‐efficacy scale, the graduates reported being more effective child behavior change agents in not only stopping child problem behavior, but also in preventing new occurrences and teaching the child appropriate behavior. These results suggest that BPT has persistent beneficial effects on children and parents. The findings reflect the program's focus on teaching parents how to use functional assessment derived positive teaching strategies to replace child problem behavior. Copyright © 2002 John Wiley & Sons, Ltd.     

Skin-to-Skin contact (Kangaroo care) promotes self-regulation in premature infants: sleep-wake cyclicity, arousal modulation, and sustained exploration

The effect of mother-infant skin-to-skin contact (kangaroo care, or KC) on self-regulatory processes of premature infants was studied. Seventy-three infants who received KC were compared with 73 infants matched for birth weight, gestational age, medical risk, and family demographics. State organization was measured in 10-s epochs over 4 hr before KC and again at term. No differences between KC infants and controls were found before KC. At term, KC infants showed more mature state distribution and more organized sleep-wake cyclicity. At 3 months, KC infants had higher thresholds to negative emotionality and more efficient arousal modulation while attending to increasingly complex stimuli. At 6 months, longer duration of and shorter latencies to mother-infant shared attention and infant sustained exploration in a toy session were found for KC infants. The results underscore the importance of maternal body contact for infants' physiological, emotional, and cognitive regulatory capacities.     

What do graded effects of semantic transparency reveal about morphological processing?

We examined the influence of semantic transparency on morphological facilitation in English in three lexical decision experiments. Decision latencies to visual targets (e.g., CASUALNESS) were faster after semantically transparent (e.g., CASUALLY) than semantically opaque (e.g., CASUALTY) primes whether primes were auditory and presented immediately before onset of the target (Experiment 1a) or visual with an stimulus onset asynchrony (SOA) of 250 ms (Experiment 1b). Latencies did not differ at an SOA of 48 ms (Experiment 2) or with a forward mask at an SOA of 83 ms (Experiment 3). Generally, effects of semantic transparency among morphological relatives were evident at long but not at short SOAs with visual targets, regardless of prime modality. Moreover, the difference in facilitation after opaque and transparent primes was graded and increased with family size of the base morpheme.     

Graded aspects of morphological processing: task and processing time

Effects on targets of orthographically (O) and semantically (S) related primes were compared with morphologically related (M) primes in the lexical decision, naming, and go/no go naming tasks. The overall pattern typified the graded nature of morphological processing. Morphological relatedness produced facilitation whose magnitude varied across a range of stimulus onset asynchronies (SOAs of 66-300 ms) and tasks. The effect of semantic and orthographic similarity also depended on SOA and on task. Importantly, the effects of morphological relatedness and orthographic similarity diverged along a time course that reflected semantic processing but could only be approximated by the effect of semantic relatedness between prime and target.