Understanding the structural determinants of object confusion in memory: an assessment of psychophysical approaches to estimating visual similarity

Computer-generated shapes varying on visual dimensions such as curvature, tapering, and thickness have been used to investigate identification deficits in the category-specific visual agnosia (CSVA) Patient E.L.M.. However, whether the implemented variations on each of these dimensions were perceived by novice observers as "similar amounts of change" is unknown. To estimate distance in psychophysical shape space, sets of shapes were developed using two different scaling methods--an objective method based on visual search, and a subjective method based on judgments of similarity--and a third approach that did not involve scaling. How well each method estimated psychophysical shape space was assessed by measuring the confusions within memory among the shapes. The results suggested that, although neither of the approaches perfectly reflected psychophysical shape space, subjective scaling was a better estimator of distance in psychophysical shape space than were other approaches. The number of confusions produced on each set of shapes was used to develop a new set of shapes that accurately estimated distance in psychophysical shape space. These results suggest that a combination of approaches is preferable in order to accurately estimate distance in psychophysical shape space.     

Laboratory behavioral measures of impulsivity

Previous research and theory have conceptualized impulsivity as a multifaceted construct that requires multiple modes of measurement for accurate assessment. This article describes a software package that includes four paradigms for measuring multiple and unique aspects of impulsivity. Specifically, four tasks are described: (1) the two choice impulsivity paradigm, (2) the single key impulsivity paradigm, (3) the GoStop impulsivity paradigm, and (4) the time paradigm. These tasks measure processes related to the capacity to tolerate delay for reward, to inhibit an already initiated response, and to estimate the passage of time. These processes have been found to be important to the understanding of impulsive behaviors. The programs are flexible and allow the experimenter to manipulate a number of parameters related to delay-reward contingencies, timing, performance feedback/payment, and data output variables. Manipulation of these parameters makes the paradigms scalable to a wide range of ability levels and appropriate for samples ranging from children to adults. The four paradigms in this software package are available at no cost and can be obtained by contacting the corresponding author.     

Anomaly detection in the right hemisphere: The influence of visuospatial factors

Previous research with both brain-damaged and neurologically intact populations has demonstrated that the right cerebral hemisphere (RH) is superior to the left cerebral hemisphere (LH) at detecting anomalies (or incongruities) in objects (Ramachandran, 1995; Smith, Tays, Dixon, & Bulman-Fleming, 2002). The current research assesses whether the RH advantage for anomaly detection is due to the RH superiority for visuospatial skills or is a distinct cognitive process. Sixty undergraduate participants completed tasks assessing anomaly detection, mental rotation, and global and local perceptual abilities. The results demonstrate that anomaly detection is negatively correlated with mental rotation. These findings suggest that anomaly detection is not simply a function of visuospatial skills.     

Attendance probabilities of participants in a human experiment

This study investigated how different prompting strategies affected the attendance probabilities of 60 undergraduate students participating in an experiment. Subjects were randomly assigned to one of three conditions: no prompt, phone-message prompt, or phone-voice prompt. Analysis showed that participants in the no-prompt condition attended the study at a rate of 50%. Participants who received a phone-message prompt attended at a rate of 55%, while participants who received a phone-voice prompt attended at a rate of 100%.     

The Relation Between Coordinated Interpersonal Timing and Maternal Sensitivity in Four-Month-Old Infants

The relation between mother–infant coordinated interpersonal timing, an automated microanalytic measure of dyadic vocal coordination, and maternal sensitivity was explored. Thirty-five mothers and their developmentally normal 4-month-old infants were audio-recorded during a 20-min laboratory vocal interaction session, that was later analyzed for degree of vocal coordination. Maternal Sensitivity ratings (Ainsworth & Bell, 1969) were based on a video-taped 45-min unstructured laboratory interaction period. A significant curvilinear relation between the degree to which mother coordinated her noninterruptive co-occurring speech to that of her infant was found and revealed that mothers highest in sensitivity were characterized by moderate levels of coordination. Examining mother-infant interaction at the specific behavioral level, while incorporating tests of nonlinear trends, may provide important information about the nature of sensitive parenting.     

Seeing double: the role of meaning in alphanumeric-colour synaesthesia

When PD, an alphanumeric-colour synaesthete, is shown black digits or letters, each grapheme elicits a highly specific colour, called a "photism" (e.g., a 2 induces green, a Z induces brown). Previous experiments showed that photisms interfere with video-colour naming when the photism colour and the video colour are incongruent. Here we used coloured ambiguous graphemes that could be interpreted as either digits or letters depending on context (e.g., an ambiguous grapheme was interpreted as a 2 if presented within a block of digit trials, but as a Z if presented within a block of letter trials). Ambiguous graphemes were presented in video colours that were either congruent or incongruent with PD's photisms. Crucially, what was a congruent trial in one context was an incongruent trial in the other context. PD's pattern of response times indicated that identical graphemes could induce differently coloured photisms depending on their interpretation. This suggests that the meaning of graphemes ultimately determines their synaesthetic colour.     

Synaesthetic photisms guide attention

We evaluated whether synaesthetic colour experiences (i.e., photisms) guide or attract attention. An alphanumeric-colour synaesthete, J, and seven non-synaesthetes searched for target digits presented against backgrounds that were either congruent or incongruent with the colours of J's photisms for the target digits. For J, the slope of the search function for detecting the target digits on incongruent trials was shallower than the slope of the search function for detecting the target digits on congruent trials. In contrast, for the seven non-synaesthetes, the slopes of the search functions for detecting the target digits on congruent and incongruent trials were equivalent. These findings suggest that synaesthetic colour experiences influence the efficiency of visual search by guiding or attracting attention.     

Latent change models of adult cognition: are changes in processing speed and working memory associated with changes in episodic memory?

The authors used 6-year longitudinal data from the Victoria Longitudinal Study (VLS) to investigate individual differences in amount of episodic memory change. Latent change models revealed reliable individual differences in cognitive change. Changes in episodic memory were significantly correlated with changes in other cognitive variables, including speed and working memory. A structural equation model for the latent change scores showed that changes in speed and working memory predicted changes in episodic memory, as expected by processing resource theory. However, these effects were best modeled as being mediated by changes in induction and fact retrieval. Dissociations were detected between cross-sectional ability correlations and longitudinal changes. Shuffling the tasks used to define the Working Memory latent variable altered patterns of change correlations.     

Generating initial models for reasoning

Much of the knowledge that children and adults have about the world resides in intuitive models. Previous work shows that intuitive models allow for computation of specific outcomes given information about the system, but little is known about how such models are acquired. The current study tested three hypotheses about how children and adults construct intuitive models when they encounter a new property: (1) intuitive models are constructed by transferring principles from familiar properties; (2) with development, children shift from applying a default model to constructing specialized models; and (3) younger children's model construction is constrained by the domain, but becomes increasingly domain independent with development. Participants from three age groups (10, 13, and 19 years) made a series of judgments about two familiar properties and one novel property. Causal models showed that all age groups transferred principles from the familiar properties to the novel property. None of the age groups used a default model. There was developmental change in the effect of domain; younger, but not older, children's models were affected by domain. These findings suggest that the transfer process is developmentally invariant but that constraints on the process (i.e., domain dependence and understanding of base models) change with development.