Calculation of signal detection theory measures

Signal detection theory (SDT) may be applied to any area of psychology in which two different types of stimuli must be discriminated. We describe several of these areas and the advantages that can be realized through the application of SDT. Three of the most popular tasks used to study discriminability are then discussed, together with the measures that SDT prescribes for quantifying performance in these tasks. Mathematical formulae for the measures are presented, as are methods for calculating the measures with lookup tables, computer software specifically developed for SDT applications, and general purpose computer software (including spreadsheets and statistical analysis software).     

Visual selection mediated by location: Feature-based selection of noncontiguous locations

Experiments using two different methods and three types of stimuli tested whether stimuli at nonadjacent locations could be selected simultaneously. In one set of experiments, subjects attended to red digits presented in multiple frames with green digits. Accuracy was no better when red digits appeared successively than when pairs of red digits occurred simultaneously, implying allocation of attention to the two locations simultaneously. Different tasks involving oriented grating stimuli produced the same result. The final experiment demonstrated split attention with an array of spatial probes. When the probe at one of two target locations was correctly reported, the probe at the other target location was more often reported correctly than were any of the probes at distractor locations, including those between the targets. Together, these experiments provide strong converging evidence that when two targets are easily discriminated from distractors by a basic property, spatial attention can be split across both locations.     

Learning Painting Styles: Spacing is Advantageous when it Promotes Discriminative Contrast

Repetitions that are distributed over time benefit long‐term retention more than when massed. Recent research has suggested that the advantage of spacing may extend to induction learning‐‐learners were better able to identify the artists of previously unseen paintings when, during training, artists' paintings were spaced (paintings by different artists were interleaved) rather than massed (a given artist's paintings were blocked and presented consecutively). Increasing temporal spacing between paintings while maintaining a presentation sequence that was blocked by artist produced test performance no better than massed presentation (both worse than interleaved presentation) (Experiment 1). Displaying paintings by different artists simultaneously produced test performance as good as interleaved presentation and better than massed presentation (Experiment 2). Our findings argue that spacing benefits perceptual induction learning not because of increased temporal spacing per se but rather because interleaving paintings by different artists enhances discriminative contrast between the artists' styles. Copyright © 2011 John Wiley & Sons, Ltd.     

Distinguishing different strategies of across-dimension attentional selection

Selective attention in multidimensional displays has usually been examined using search tasks requiring the detection of a single target. We examined the ability to perceive a spatial structure in multi-item subsets of a display that were defined either conjunctively or disjunctively. Observers saw two adjacent displays and indicated whether the to-be-selected items within the two displays matched in terms of their spatial structure (the identity of the corresponding items within these subsets was not relevant to the task). The observers in our study could readily perceive conjunctively defined subsets, but had great difficulty with disjunctively defined subsets. The results pose a challenge to the popular idea that attention is guided by a "priority map" that sums bottom-up and top-down factors, whereas they are directly predicted by Boolean map theory of visual attention.     

The perceptual span during foveally-demanding visual target localization

Foveally-induced processing load deteriorates target localization performance in vision-guided tasks. Here, participants searched for a target embedded among coded distractors. High processing load was effected by instructing some participants to use the coded distractors to guide their search for the target. Other participants (in the low processing load condition) were not apprised of the code. The experiment examined whether increased processing load alters the span of effective processing (i.e. perceptual span) by (a) reducing its size, (b) altering its shape, or (c) reducing its size and altering its shape. The results demonstrated a reduction in the size of the perceptual span, with no significant change to its shape. It is argued that when distractors are processed beyond simply rejecting them as non targets, the perceptual span shrinks with increasing processing load. The findings are discussed in contrast to a general interference theory that predicts a change in vision-guided performance without a shrinking of the perceptual span.     

Testing orofacial abilities of children who stutter: the Movement, Articulation, Mandibular and Sensory awareness (MAMS) assessment procedure

Objective

The purpose of this article is to introduce a new assessment designed to measure the orofacial abilities of children who stutter (CWS), the Movement, Articulation, Mandibular and Sensory Awareness (MAMS) Orofacial Assessment. The new instrument was developed and validated to measure orofacial abilities in a comprehensive manner.

Design

A group of 43 CWS (mean age 13.10 years, S.D. 2.10 years) and a control group of 32 fluent children (mean age 13.4 years, S.D. 2.6 years) were tested with the new tool. It was hypothesized, that (a) the MAMS is a reliable and valid instrument to measure orofacial abilities in CWS, (b) fluent children have better orofacial abilities than CWS and (c) that the therapy outcome of CWS depend on their orofacial abilities.

Results

The MAMS Orofacial Assessment proved to be a valid and reliable instrument to assess orofacial abilities. Compared with their fluent peers, CWS had significantly worse orofacial abilities. CWS with better orofacial abilities had a better prognosis for therapy outcome.

Conclusions

The new instrument is a reliable and valid tool to measure orofacial abilities and MAMS distinguishes CWS and controls. Orofacial abilities are one set of factors that influence therapy outcome for CWS.Educational objectives: The reader will get an overview over of the literature on orofacial abilities in people who stutter and will learn about and be able to (1) describe different characteristics of orofacial abilities, (2) use the MAMS Orofacial Assessment in the diagnostic process for CWS and for research purposes, and (3) interpret the results of the MAMS to use them for therapy planning.     

The Stammering Information Programme: a Delphi study

Purpose

To find out what information children, parents and education staff feel would be important to know to support a child who stutters in the educational environment, in order to develop appropriate resources.

Method

A Delphi study was carried out to seek the opinions of experts about the information to include. A structured six stage process was completed in order to gain consensus within four expert panels: children who stutter (CWS) aged 7-11 (n = 25); young people who stutter aged 12-18 (n = 27); parents of children and young people who stutter aged 2-18 (n = 67); and members of the education workforce (n = 35).

Results

In response to the questions, 538 statements were generated across the four expert panels, categorised and reduced to 276. Of the 154 rating questionnaires sent out, 99 were returned (64.2% response rate). The top 32 statements, which were those most highly rated and with the greatest consensus, were retained to inform the resources.

Conclusions

This study demonstrates the value of including service users when devising materials aimed for the benefit of CWS. The methodology employed ensured that ideas, perceptions and needs were representative of a range of people who experience stuttering from different perspectives. The results indicated that each expert panel had different priorities of what should be included. The resulting resources may therefore be considered to have high content validity and would be predicted to meet the needs of those who require them.Educational Objectives: The reader will be able to (1) define the Delphi Approach (2) discuss the development of a user led resource for raising awareness about stuttering.