Consolidation theory and retrograde amnesia in humans

Recent research on the cognitive dysfunctions experienced by human anmesic patients indicates that very long term (multidecade) changes may occur in memory.Flat retrograde amnesia (RA), consisting of a uniform memory deficit for information from all preamnesia time periods, indicates a simple, monolithic retrieval problem, whereasgraded RA, with greater memory deficits for information from recent as opposed to remote time periods, suggests the presence of a gradual long-term encoding, or consolidation, process. An evaluation of 247 outcomes from 61 articles provides strong evidence of graded RA across different cerebral injuries, materials, and test procedures, as well as in measures of both absolute and relative (patient vs. control) performance. Future conceptualizations of human memory should address the possibility that memories increase in resistance to forgetting, or reduction in trace fragility, across many decades.     

A crossmodal attentional blink between vision and touch

There is currently a great deal of interest regarding the possible existence of a crossmodal attentional blink (AB) between audition and vision. The majority of evidence now suggests that no such crossmodal deficit exists unless a task switch is introduced. We report two experiments designed to investigate the existence of a crossmodal AB between vision and touch. Two masked targets were presented successively at variable interstimulus intervals. Participants had to respond either to both targets (experimental condition) or to just the second target (control condition). In Experiment 1, the order of target modality was blocked, and an AB was demonstrated when visual targets preceded tactile targets, but not when tactile targets preceded visual targets. In Experiment 2, target modality was mixed randomly, and a significant crossmodal AB was demonstrated in both directions between vision and touch. The contrast between our visuotactile results and those of previous audiovisual studies is discussed, as are the implications for current theories of the AB.     

Measures of self-efficacy and optimism in older adults with generalized anxiety

This study provides initial psychometric data for the Self-Efficacy Scale (SES) and the Life Orientation Test (LOT) in a sample of older adults with generalized anxiety disorder (GAD). Participants included 76 adults, ages 60 to 80, who met Diagnostic and Statistical Manual of Mental Disorders (4th ed.) criteria for GAD. Self-efficacy and outcome expectancies were lower in older adults with GAD relative to published data from younger and older community samples. Both the SES and LOT demonstrated adequate internal consistency. Confirmatory factor analysis provided evidence for optimism and pessimism factors within the LOT and exploratory factor analysis of the SES suggested threefactors that overlap with previous findings. Overall, the data support the potential utility of these instruments in late-life GAD and set the stage forfuture investigations of generalized self-efficacy expectancies and outcome expectancies (or optimism) as they relate to the prediction of affect and behavior in this group.     

Processing Coordinate Structures

Coordination often involves syntactically like categories. Based on the results of four reading time studies, it is argued here that the syntactic like-category restriction is not grammatical. Coordination of unlike categories can be just as acceptable as coordination of like categories. However, syntactically like category coordination is processed faster than coordination of unlike categories even when the two sentence types are judged to be fully acceptable. Further, parallelism of conjuncts facilitates processing regardless of whether it is parallelism in the category of the conjuncts (a property which the grammar might regulate) or parallelism in the internal structure of the conjuncts (a property which the grammar does not regulate, on anyone's view). Parallelism did not facilitate processing when the structure of a subject and object were manipulated, implying that parallelism effects are largely limited to the conjuncts of a coordinate structure and not due simply to the repetition of a phrase with a particular shape.     

Task switching and the measurement of “switch costs”

The measurement of “switch costs” is held to be of interest because, as is widely believed, they may reflect the control processes that are engaged when subjects switch between two (or more) competing tasks. [In task-switching experiments, the reaction time (RT) switch cost is typically measured as the difference in RT between switch and non-switch (repeat) trials.] In this report we focus on the RT switch costs that remain even after the subject has had some time to prepare for the shift of task, when the switch cost may be approximately asymptotic (so-called residual switch costs). Three experiments are presented. All three experiments used Stroop colour/word, and neutral stimuli. Participants performed the two tasks of word-reading and colour-naming in a regular, double alternation, using the “alternating runs” paradigm (R. D. Rogers & S. Monsell, 1995). The experiments were designed to test the hypothesis that RT switch costs depend on a form of proactive interference (PI) arising from the performance of a prior, competing task. A. Allport, E. A. Styles and S. Hsieh (1994) suggested that these PI effects resulted from “task-set inertia”, that is, the persisting activation-suppression of competing task-sets, or competing task-processing pathways. The results confirmed the existence of long-lasting PI from the competing task as a major contributor to switch costs. Non-switch trials, used as the baseline in the measurement of switch costs, were also shown to be strongly affected by similar PI effects. However, task-set inertia was not sufficient to account for these results. The results appeared inconsistent also with all other previous models of task switching. A new hypothesis to explain these between-task interference effects was developed, based on the stimulus-triggered retrieval of competing stimulus-response (S-R) associations, acquired (or strengthened) in earlier trials. Consistent with this retrieval hypothesis, switch costs were shown to depend primarily on the S-R characteristics of the preceding task (the task that was switched from) rather than the upcoming task. Further, the effects of the other, competing task were found to persist over many successive switching trials, affecting switch costs long after the stimulus overlap (and hence the principal S-R competition) between the current tasks had been removed. Switch costs were also found to be affected by recent, item-specific experience with a given stimulus, in either the same or the competing task. Finally, the results showed that switch costs were massively affected by the ratio of the number of prior trials, in response to the same stimuli, that had implemented either the currently intended or the competing S-R mappings. None of these effects are predicted by current models of residual switch costs, which appeal to the differences in control processes assumed to be engaged in switch versus non-switch trials. Received: 31 March 1999 / Accepted: 23 July 1999     

Suicide among adolescents and young adults: a cross-national comparison of 34 countries

Few cross-national reports have examined suicide rates among adolescents and young adults. A survey of suicides among 15-24-year-olds in 34 of the wealthiest nations demonstrated that 15,555 youths killed themselves in a 1-year study period. Thirty-four percent of these suicides were firearm-related. Finland led the participating nations in total and firearm-related suicide rates. An association was found between divorce rates and youth suicide rates, firearm-related suicide among youths, and suicide rates among young males. For a smaller sample of countries, an association was found between firearm availability and firearm-related suicide rates among youths and suicide rates among young males.     

Is inhibition of return a reflexive effect?

The inhibition of return (IOR) phenomenon is routinely considered an effect of reflexive attention because the paradigm used to generate IOR employs peripheral cues that are uninformative as to where a target will appear. Because the cues are spatially unreliable it is thought that there is no reason for attention to be committed volitionally to them, and hence, the IOR effect is considered reflexive. What has been generally overlooked, however, is that the cues provide reliable temporal information as to when a target will occur. This predictive information is used by participants to prepare volitionally for when a target is likely to appear. We investigated whether the IOR effect is a product of the volitional application of attention to peripheral cues for the use of their temporal information. To test this idea we rendered the temporal information provided by peripheral cues unreliable. While this eliminated participants using the cues volitionally, it did not abolish the IOR phenomenon. These data demonstrate two new findings. First, the IOR effect is fundamentally a reflexive phenomenon. Second, when peripheral cues are not used volitionally, the IOR effect is attenuated. Together, the present findings indicate that the IOR effect can be modulated by volitional (top-down) processes but it is not the product of them. We argue that an intimate link between fronto-parietal regions and the superior colliculus provide a functional neural mechanism for this volitional effect to impact IOR.     

Developmental changes in the relationship between the infant's attention and emotion during early face-to-face communication: the 2-month transition

Weekly observations documented developmental changes in mother-infant face-to-face communication between birth and 3 months. Developmental trajectories for each dyad of the duration of infant facial expressions showed a change from the dominance of Simple Attention (without other emotion expressions) to active and emotionally positive forms of attention to the mother toward the end of the 2nd month. The results support an overlapping waves model, rather than a stage model, of developmental change. Sequential analysis found developmental changes from cycling between Gaze Elsewhere and Simple Attention to the Mother's Face in the early weeks to a complex sequence of transitions between Concentrated Attention, Smile, and Cooing Expression nested into sequences of positive communication during the 2nd and 3rd months.