Prospective memory and ageing: Is task importance relevant?

Memory for activities to be performed in the future, i.e., prospective memory, such as remembering to take medication or remembering to give a colleague a message, is a pervasive real‐world memory task that has recently begun to attract the attention of numerous researchers. Age effects in prospective memory have been found particularly in complex paradigms requiring participants to remember to switch between several subtasks in a limited time period (e.g., Kliegel, McDaniel, & Einstein, 2000). Here, most of the older adults try to complete one or two subtasks and to forget the prospective instruction to work on all subtasks. Since recent findings in this context show that one profits from tips regarding the relevant task in complex double tasks, it seems likely that age effects in prospective memory tasks might also be due to the lack of information about the importance of the prospective task. To test this hypothesis, the importance of the prospective task was varied in the present study with 104 young and old participants by providing motivational incentives to interrupt and switch during the introduction phase (plan formation) as well as during the execution phase. Also, interindividual differences regarding nonexecutive as well as executive cognitive resources were analysed, thus allowing estimation of the relationship between these factors and (age‐related) performance in complex prospective remembering. The results show age effects in favour of the younger group in all task components of the complex prospective multitask. In contrast, there was no effect of the present experimental manipulation of motivational incentives. Finally, in regression analyses, intention formation, in particular, was found to be a significant predictor of intention execution, explaining most of the age‐related variance. In sum, our results specifically highlight the fundamental importance of adequately planning the complex intention and do not support the hypothesis that age‐related decrements in performance are reflecting a lack of motivation in the present complex prospective memory paradigm.     

Adlerian-oriented early memory research: what does it tell us?

Of the different approaches to interpreting early memories (EMs), Adlerian-oriented EM research comparatively has shown a most substantial increase in the past 10 years. I examine all Adlerian-oriented EM research appearing from 1981 through 1990. The majority of the research provides a tentative base of support for Adler's (1931) views about EMs. However, several deficiencies in these investigations are identified (e.g., a lack of pilot studies), and some recommendations are made for future EM studies.     

Communication in preterm infants: Why is it different?

The present paper selectively reviews the literature which compares full-term and preterm infants' communication with their mothers in the first year of life. The review is focused not only on what differences are found between full-term and preterm infants, but also why such differences exist. Particular emphasis is placed on the importance of interpreting the findings in the light of the developmental phase of the infants, the heterogeneity of the preterm population and the situation in which communication is studied. Most studies were not designed to consider these issues in any detail. Differences with respect to these factors can be found between studies, however, which may have contributed to the often contradictory findings. Consequently, comparisons between these studies provide clues about the effects of these factors on communicative development. The ultimate goal of this review is to point to important directions for future research on early communication in preterm infants.     

The phonological store of working memory: is it phonological and is it a store?

The phonological store construct of the working memory model is critically evaluated. Three experiments test the prediction that the effect of irrelevant sound and the effect of phonological similarity each survive the action of articulatory suppression but only when presentation of to-be-remembered lists is auditory, not visual. No evidence was found to support the interaction predicted among irrelevant speech, modality, and articulatory suppression. Although evidence for an interaction among modality, phonological similarity, and articulatory suppression was found, its presence could be diminished by a suffix, which is an acoustic, not a phonological factor. Coupled with other evidence--from the irrelevant sound effect and errors in natural speech--the action attributed to the phonological store seems better described in terms of a combination of auditory-perceptual and output planning mechanisms.     

Why is working memory related to fluid intelligence?

Nearly 1,000 adults performed a battery of cognitive tests and working memory tasks requiring simultaneous storage and processing of information. Because the amount of to-be-remembered information, or set size, varied randomly across trials, the relation between fluid intelligence and working memory could be examined across different levels of complexity and across successive trials in the working memory tasks. Strong influences of fluid intelligence were apparent in the simplest versions and on the initial trials in the working memory tasks, which suggests that the relation between working memory and fluid intelligence is not dependent on the amount of information that must be maintained, or on processes that occur over the course of performing the tasks.     

What is chaos and how is it relevant for philosophy of mind?

This paper argues, in agreement with Neuringer, Beggs and others, that if we wish to scientifically characterise human choice, we have to work with a probabilistic or chaos-derived model. This has a number of implications for philosophy of mind. Firstly, it is in theory possible to describe human behaviour with some form of law-like equation; it is just a matter of figuring out what equation best captures the states of our central nervous system. Secondly, it means that our choices are not random but are chaotic: deterministic, but just hard to predict due to internal complexity. According to the current research, our actions are most likely caused by ‘precipitated avalanches’ of neural activity, which are difficult to predict due to chaos.     

Why is it easy to control your arms ?

The complexity of our muscular systems may be regarded, not as a complication for the brain, but as a source of variety providing enough easily controlled movement recipes to do most of the things we ordinarily need to do. This simplifies the control task, in that if there are enough ways of moving, a recipe involving just a few of them can usually be found that will approximate any desired movement with little supervision. In particular, the presence of"redundant" degrees of freedom allows us to use ballistic (free swinging) movements, so that physics, rather than computation, accounts for much of trajectory. Computations are required to set up the constraints defining initializing a low-dimensional subsystem in such a way that a satisfactory movement exists. One theme of current research is that these recipes may generated by specifying the parameters of oscillators and spring-like components. We should expect actions to be represented as patchworks of recipes, each working best for some subset of variants of the action.     

What is episodic memory and how do we use it?

What are the neural and computational principles that give rise to episodic memory? Although memory is probably the most studied topic in psychology and cognitive neuroscience, most research has focused on learning at the micro-level. I outline the limitations of this approach and propose a ‘molar’ approach to tackle episodic memory at the scale of life.     

Why is information displaced from visual working memory during visual search?

Research has shown that performing visual search while maintaining representations in visual working memory displaces up to one object's worth of information from memory. This memory displacement has previously been attributed to a nonspecific disruption of the memory representation by the mere presentation of the visual search array, and the goal of the present study was to determine whether it instead reflects the use of visual working memory in the actual search process. The first hypothesis tested was that working memory displacement occurs because observers preemptively discard about an object's worth of information from visual working memory in anticipation of performing visual search. Second, we tested the hypothesis that on target absent trials no information is displaced from visual working memory because no target is entered into memory when search is completed. Finally, we tested whether visual working memory displacement is due to the need to select a response to the search array. The findings rule out these alternative explanations. The present study supports the hypothesis that change-detection performance is impaired when a search array appears during the retention interval due to nonspecific disruption or masking.     

Why is it difficult to see in the fog? How stimulus contrast affects visual perception and visual memory

Processing visually degraded stimuli is a common experience. We struggle to find house keys on dim front porches, to decipher slides projected in overly bright seminar rooms, and to read 10th-generation photocopies. In this research, we focus specifically on stimuli that are degraded via reduction of stimuluscontrast and address two questions. First, why is it difficult to process low-contrast, as compared with high-contrast, stimuli? Second, is the effect of contrastfundamental in that its effect is independent of the stimulus being processed and the reason for processing the stimulus? We formally address and answer these questions within the context of a series of nested theories, each providing a successively stronger definition of what it means for contrast to affect perception and memory. To evaluate the theories, we carried out six experiments. Experiments 1 and 2 involved simple stimuli (randomly generated forms and digit strings), whereas Experiments 3–6 involved naturalistic pictures (faces, houses, and cityscapes). The stimuli were presented at two contrast levels and at varying exposure durations. The data from all the experiments allow the conclusion that some function of stimulus contrast combines multiplicatively with stimulus duration at a stage prior to that at which the nature of the stimulus and the reason for processing it are determined, and it is the result of this multiplicative combination that determines eventual memory performance. We describe a stronger version of this theory— the sensory response, information acquisition theory—which has at its core, the strong Bloch’s-law-like assumption of a fundamental visual system response that is proportional to the product of stimulus contrast and stimulus duration. This theory was, as it has been in the past, highly successful in accounting for memory for simple stimuli shown at short (i.e., shorter than an eye fixation) durations. However, it was less successful in accounting for data from short-duration naturalistic pictures and was entirely unsuccessful in accounting for data from naturalistic pictures shown at longer durations. We discuss (1) processing differences between short- and long-duration stimuli, (2) processing differences between simple stimuli, such as digits, and complex stimuli, such as pictures, (3) processing differences between biluminant stimuli (such as line drawings with only two luminance levels) and multiluminant stimuli (such as grayscale pictures with multiple luminance levels), and (4) Bloch’s law and a proposed generalization of the concept ofmetamers.     

Is it relevant? Influence of trial manipulations of prospective memory context on task interference

The effects of blocked versus mixed presentation were tested on visual feature binding, assuming that blocked presentation enhances focused attention, whilst mixed presentation recruits extra attentional resources for intratrial as well as intertrial processing. The contextual interference effect suggests that although performance due to mixed presentation is either similar or worse than blocked presentation when tested immediately, it is better when tested after an interval. We explored whether this robust empirical effect, common in psychomotor performance, would be evident in visual feature binding. Stimuli were conjunctions of shape, colour, and location. Study–test intervals from 0 to 2,500 ms were used with a swap detection task. In Experiments 1A and 1B, participants ignored locations to detect shape–colour bindings. In Experiments 2A and 2B, they ignored shapes to detect colour–location binding. In Experiments 3A and 3B, they ignored colours to detect shape–location bindings. Whilst Experiments 1A, 2A, and 3A used blocked presentation, Experiments 1B, 2B, and 3B used mixed presentation of study–test intervals. The results of these experiments and a replication experiment using a within-subjects design showed that the contextual interference effect appeared when spatial attention was engaged, but not when attention was object based.     

Why do doctored images distort memory?

Doctored images can cause people to believe in and remember experiences that never occurred, yet the underlying mechanism(s) responsible are not well understood. How does compelling false evidence distort autobiographical memory? Subjects were filmed observing and copying a Research Assistant performing simple actions, then they returned 2 days later for a memory test. Before taking the test, subjects viewed video-clips of simple actions, including actions that they neither observed nor performed earlier. We varied the format of the video-clips between-subjects to tap into the source-monitoring mechanisms responsible for the ‘doctored-evidence effect.’ The distribution of belief and memory distortions across conditions suggests that at least two mechanisms are involved: doctored images create an illusion of familiarity, and also enhance the perceived credibility of false suggestions. These findings offer insight into how external evidence influences source-monitoring.     

Rater bias in psychological research: when is it a problem and what can we do about it?

Rater bias is a substantial source of error in psychological research. Bias distorts observed effect sizes beyond the expected level of attenuation due to intrarater error, and the impact of bias is not accurately estimated using conventional methods of correction for attenuation. Using a model based on multivariate generalizability theory, this article illustrates how bias affects research results. The model identifies 4 types of bias that may affect findings in research using observer ratings, including the biases traditionally termed leniency and halo errors. The impact of bias depends on which of 4 classes of rating design is used, and formulas are derived for correcting observed effect sizes for attenuation (due to bias variance) and inflation (due to bias covariance) in each of these classes. The rater bias model suggests procedures for researchers seeking to minimize adverse impact of bias on study findings.     

What is a Person? And Why it Matters in Religious Ethics

Here I respond to four critics of my book, What Is a Person?, seeking to find areas of common ground and crucial disagreement. Most importantly, I explore the question of whether all human knowledge is conceptually mediated, acknowledging that, no, indeed, there are likely forms of experiential knowledge that are purely and directly acquired without conceptual mediation.