Dialogues on prediction errors

The recognition that computational ideas from reinforcement learning are relevant to the study of neural circuits has taken the cognitive neuroscience community by storm. A central tenet of these models is that discrepancies between actual and expected outcomes can be used for learning. Neural correlates of such prediction-error signals have been observed now in midbrain dopaminergic neurons, striatum, amygdala and even prefrontal cortex, and models incorporating prediction errors have been invoked to explain complex phenomena such as the transition from goal-directed to habitual behavior. Yet, like any revolution, the fast-paced progress has left an uneven understanding in its wake. Here, we provide answers to ten simple questions about prediction errors, with the aim of exposing both the strengths and the limitations of this active area of neuroscience research.     

Ontological issues in distance perception: cue use under full cue conditions cannot be inferred from use under controlled conditions

Phosphorescent square tiles (arranged to yield a single image size) were viewed in the dark by 56 monocular observers who utilized a chinrest. The targets were placed at one of three horizontal distances and at one of three eye heights, allowing us to study the relative effect of height in the visual field (HVF) and sagittal distance on observers' verbal reports of the horizontal distance at which the object lay (near, middle, or far). In Experiment 1, we found that reports covaried primarily with HVF and, as predicted, they exhibited a weak paradoxical inverse relation with horizontal distance. In a second and third experiment, a visible surface was placed under the targets at the three eye heights in both dark and fully lighted conditions. In this situation, the inverse distance relation disappeared, and HVF no longer influenced the judgments of most observers. The results show that information projected from relevant support surfaces is essential for veridical information about object distance. These results raise fundamental issues for perceptual researchers regarding how to decide when a cue has been properly delineated, given the assumption that the relation between a cue and what it specifies is probabilistic.     

Attentional and automatic processes in line tracing: is tracing obligatory?

When comparing two target elements placed on the same convoluted curve, response times are dependent on the distance between the targets along the curve, despite being separated by a constant Euclidean distance. The present study assessed whether such line tracing is obligatory across the whole of the line even when the task demands do not require it, or whether it is an optional strategy that can be disregarded when the circumstances favor a different method of attentional deployment. Three experiments were conducted to assess whether attention can select only a portion of a curve to trace when it is strategically sensible to do so. The results suggest that attention can indeed jump over portions of a line that are irrelevant to task performance before tracing has begun. However, the final experiment suggests that line tracing may continue beyond the task-relevant portion of the line. We conclude that line tracing is a strategy whose initial deployment can be influenced by top-down factors, rather than an obligatory response triggered by the stimuli-although, once engaged, line tracing may be hard to stop.     

Testing a self-determination theory intervention for motivating tobacco cessation: supporting autonomy and competence in a clinical trial.

A longitudinal randomized trial tested the self-determination theory (SDT) intervention and process model of health behavior change for tobacco cessation (N = 1006). Adult smokers were recruited for a study of smokers' health and were assigned to intensive treatment or community care. Participants were relatively poor and undereducated. Intervention patients perceived greater autonomy support and reported greater autonomous and competence motivations than did control patients. They also reported greater medication use and significantly greater abstinence. Structural equation modeling analyses confirmed the SDT process model in which perceived autonomy support led to increases in autonomous and competence motivations, which in turn led to greater cessation. The causal role of autonomy support in the internalization of autonomous motivation, perceived competence, and smoking cessation was supported.     

How does the purpose of inspection influence the potency of visual salience in scene perception?

Salience-map models have been taken to suggest that the locations of eye fixations are determined by the extent of the low-level discontinuities in an image. While such models have found some support, an increasing emphasis on the task viewers are performing implies that these models must combine with cognitive demands to describe how the eyes are guided efficiently. An experiment is reported in which eye movements to objects in photographs were examined while viewers performed a memory-encoding task or one of two search tasks. The objects depicted in the scenes had known salience ranks according to a popular model. Participants fixated higher-salience objects sooner and more often than lower-salience objects, but only when memorising scenes. This difference shows that salience-map models provide useful predictions even in complex scenes and late in viewing. However, salience had no effects when searching for a target defined by category or exemplar. The results suggest that salience maps are not used to guide the eyes in these tasks, that cognitive override by task demands can be total, and that modelling top-down search is important but may not be easily accomplished within a salience-map framework.     

A National Survey of State Legislation defining mental retardation: implications for policy and practice after Atkins

In Atkins v. Virginia 2002, the U.S. Supreme Court held that the Eighth Amendment prohibits executing offenders who are mentally retarded. Rather than adopting a uniform definition of mental retardation, the court charged each state with defining mental retardation in a manner that enforces the constitutional restriction. An unanswered question is how states define mental retardation after Atkins, which has implications for capital defendants and forensic evaluators who conduct capital mitigation evaluations. This project identified the statutory definitions of mental retardation in each state, and grouped the definitions based on consistency with accepted clinical criteria for mental retardation. Results show that definitions of mental retardation vary considerably by state. The large majority of states, both overall and specifically among death penalty states, use criteria for mental retardation that are not entirely consistent with accepted clinical standards. As such, it is not clear whether the majority of states are effectuating the intent of Atkins. The implications of these findings for both policy and practice are discussed.     

Implicit memory influences the allocation of attention in visual cortex

The visual environment is highly regular, with particular objects frequently appearing in specific locations. Previous studies of visual search have shown that people take advantage of such regularities, detecting targets more quickly when they appear at a predictable location within a given spatial configuration. Moreover, this effect depends on implicit rather than explicit memory for the configurations. These studies have suggested that implicit long-term memory for contextual information influences the allocation of attention, modulating the flow of information through visual cortex. The present study used event-related potentials to provide the first direct support for this proposal. We suggest that this guidance of attention by implicit memory is important in the natural environment because it allows environmental regularities to influence perception without the intervention of limited-capacity conscious processes.     

Emulation vs. indigenization in the reception of western psychology in Republican China: An analysis of the content of Chinese psychology journals (1922–1937)

The present study examines the practice of empirical psychology in China during the Republican period using a content analysis of its journals. By seeking answers to questions of what kinds of psychology from the West first attracted the Chinese; whether they found a way of developing a psychology more in tune to their own cultural assumptions of selfhood; and to what uses they felt the new discipline could be put, it shows the extent to which its journal content adopted a Western or an indigenous orientation. It thus contributes to the recent debate about indigenization of psychology globally and situates the origins of these issues in China much earlier than has been envisaged by contemporary Chinese indigenous psychologists. Throughout this period, indigenous concerns informed the research agenda, the dominant practice being psychometrics. But because of a lack of social support, they remained largely confined to the pages of psychology journals. © 2009 Wiley Periodicals, Inc.     

Does a fitness factor contribute to the association between intelligence and health outcomes? Evidence from medical abnormality counts among 3654 US Veterans

We suggest that an over-arching ‘fitness factor’ (an index of general genetic quality that predicts survival and reproductive success) partially explains the observed associations between health outcomes and intelligence. As a proof of concept, we tested this idea in a sample of 3654 US Vietnam veterans aged 31–49 who completed five cognitive tests (from which we extracted a g factor), a detailed medical examination, and self-reports concerning lifestyle health risks (such as smoking and drinking). As indices of physical health, we aggregated ‘abnormality counts’ of physician-assessed neurological, morphological, and physiological abnormalities in eight categories: cranial nerves, motor nerves, peripheral sensory nerves, reflexes, head, body, skin condition, and urine tests. Since each abnormality was rare, the abnormality counts showed highly skewed, Poisson-like distributions. The correlation matrix amongst these eight abnormality counts formed only a weak positive manifold and thus yielded only a weak common factor. However, Poisson regressions showed that intelligence was a significant positive predictor of six of the eight abnormality counts, even controlling for diverse lifestyle covariates (age, obesity, combat and toxin exposure owing to service in Vietnam, and use of tobacco, alcohol, marijuana, and hard drugs). These results give preliminary support for the notion of a superordinate fitness factor above intelligence and physical health, which could be further investigated with direct genetic assessments of mutation load across individuals.