Two hands are better than one: a new assessment method and a new interpretation of the non-visual illusion of self-touch

A simple experimental paradigm creates the powerful illusion that one is touching one’s own hand even when the two hands are separated by 15 cm. The participant uses her right hand to administer stimulation to a prosthetic hand while the Examiner provides identical stimulation to the participant’s receptive left hand. Change in felt position of the receptive hand toward the prosthetic hand has previously led to the interpretation that the participant experiences self-touch at the location of the prosthetic hand, and experiences a sense of ownership of the prosthetic hand. Our results argue against this interpretation. We assessed change in felt position of the participant’s receptive hand but we also assessed change in felt position of the participant’s administering hand. Change in felt position of the administering hand was significantly greater than change in felt position of the receptive hand. Implications for theories of ownership are discussed.     

The multinomial model of prospective memory: validity of ongoing-task parameters

The objective of this research was to provide additional experimental validation of the multinomial processing tree (MPT) model of event-based prospective memory (Smith & Bayen, 2004). In particular, the parameters that measure trial-type detection in the ongoing task were examined. In three experiments with different response instructions, event-based prospective memory tasks were embedded in ongoing color-matching tasks. The results support the validity of the MPT model, that is, manipulations of ongoing-task difficulty affected the ongoing-task parameters of the MPT model, while leaving the estimates for the prospective and the retrospective components of prospective memory unaffected.     

Spatial limits on the nonvisual self-touch illusion and the visual rubber hand illusion: Subjective experience of the illusion and proprioceptive drift

The nonvisual self-touch rubber hand paradigm elicits the compelling illusion that one is touching one’s own hand even though the two hands are not in contact. In four experiments, we investigated spatial limits of distance (15 cm, 30 cm, 45 cm, 60 cm) and alignment (0°, 90° anti-clockwise) on the nonvisual self-touch illusion and the well-known visual rubber hand illusion. Common procedures (synchronous and asynchronous stimulation administered for 60 s with the prosthetic hand at body midline) and common assessment methods were used. Subjective experience of the illusion was assessed by agreement ratings for statements on a questionnaire and time of illusion onset. The nonvisual self-touch illusion was diminished though never abolished by distance and alignment manipulations, whereas the visual rubber hand illusion was more robust against these manipulations. We assessed proprioceptive drift, and implications of a double dissociation between subjective experience of the illusion and proprioceptive drift are discussed.     

Prospective memory in young and older adults: The effects of ongoing-task load

ABSTRACT

Prospective memory involves remembering to perform intended actions in the future. Previous work with the multinomial model of event-based prospective memory indicated that adult age-related differences in prospective-memory performance were due to the prospective (not the retrospective) component of the task (Smith & Bayen, 2006 Smith, R. E. and Bayen, U. J. 2006. The source of age differences in event-based prospective memory: A multinomial modeling approach. Journal of Experimental Psychology: Learning, Memory, and Cognition, 32: 623–635. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar], Journal of Experimental Psychology: Learning, Memory, and Cognition, 32, 623). However, ongoing-task performance was also lower in older adults in that study. In the current study with young and older adults, the difficulty of the ongoing task was manipulated by varying the number of colors per trial to create easier and harder versions of the ongoing task for each age group. The easier version included 2 colors per trial for older adults and 4 colors for young adults. The harder version included 4 colors for older adults and 6 colors for young adults. By adjusting the ongoing-task difficulty, older adults were able to perform the ongoing task as well or better than the young adults. Analyses with the multinomial model revealed that making the ongoing task easier for older adults (or more difficult for young adults) did not eliminate age-related differences in prospective-memory performance and the underlying prospective component.     

Adult age differences in distinctive processing: the modality effect on false recall

Age differences in distinctive processing were investigated by examining the effects of study presentation modality on false recall in younger and older adults using the Deese/Roediger and McDermott paradigm. Participants were presented with study words either visually or auditorily. Older adults did not show the typical reduction in false recall after visual, compared to auditory, study presentation (R.E. Smith & R.R. Hunt, 1998). The authors interpret these results as evidence of reduced distinctive processing on the part of older adults.     

A multinomial model of event-based prospective memory

Prospective memory is remembering to perform an action in the future. The authors introduce the 1st formal model of event-based prospective memory, namely, a multinomial model that includes 2 separate parameters related to prospective memory processes. The 1st measures preparatory attentional processes, and the 2nd measures retrospective memory processes. The model was validated in 4 experiments. Manipulations of instructions to place importance on either the prospective memory task or the background task (Experiments 1 and 2) and manipulations of distinctiveness of prospective memory targets (Experiment 2) had expected effects on model parameters, as did a manipulation of the difficulty of prospective memory target encoding (Experiments 3 and 4). An alternative model was also evaluated.     

Habitual Prospective Memory and Aging: Remembering Intentions and Forgetting Actions

Routine or habitual prospective memory tasks (e.g., taking medication) have the potential for creating confusions regarding whether or not an action has already been performed. We developed a laboratory paradigm for examining the kinds of processes thought to be operating in these kinds of tasks. Younger and older participants were asked to perform an action once and only once on each of 11 trials. The results showed that age and divided attention contributed to both omission and repetition errors. This new paradigm reveals memory failures in a habitual prospective memory task, and the results demonstrate that older adults are particularly susceptible to these memory problems.     

Perceptions of the Efficacy of Prayer and Conventional Medicine for Health Concerns

Previous research has associated prayer practices with positive health outcomes, but few studies have examined: (a) the perceptions of prayer in relation to perceptions of the efficacy of conventional medicine, and (b) whether the perceptions of prayer efficacy differ based on illness type, context of prayer, and whether prayer is for the self or someone else. The current study surveyed 498 emerging adults at a public university. Conventional medicine was perceived as more effective for alleviating health concerns overall, but participants perceived prayer as most effective when performed in a group setting for someone else. Individuals perceived prayer as more effective than conventional medicine when they reported greater religious activity, lower health locus of control, and higher spiritual locus of control.

     

The effects of working memory resource availability on prospective memory: a formal modeling approach

The PAM theory of event-based prospective memory (Smith, 2003; Smith & Bayen, 2004a) proposes that successful prospective memory performance demands upon the interaction of preparatory attentional processes and retrospective memory processes. The two experiments in the current study represent the first application of a formal model to investigate the sensitivity of these underlying processes to variations in working memory resource availability. Multinomial modeling of data from prospective-memory tasks showed that working memory span influenced preparatory attentional processes and retrospective-memory processes.