Evidence for the contribution of a threshold retrieval process to semantic memory

It is widely held that episodic retrieval can recruit two processes: a threshold context retrieval process (recollection) and a continuous signal strength process (familiarity). Conversely the processes recruited during semantic retrieval are less well specified. We developed a semantic task analogous to single-item episodic recognition to interrogate semantic recognition receiver-operating characteristics (ROCs) for a marker of a threshold retrieval process. We fitted observed ROC points to three signal detection models: two models typically used in episodic recognition (unequal variance and dual-process signal detection models) and a novel dual-process recollect-to-reject (DP-RR) signal detection model that allows a threshold recollection process to aid both target identification and lure rejection. Given the nature of most semantic questions, we anticipated the DP-RR model would best fit the semantic task data. Experiment 1 (506 participants) provided evidence for a threshold retrieval process in semantic memory, with overall best fits to the DP-RR model. Experiment 2 (316 participants) found within-subjects estimates of episodic and semantic threshold retrieval to be uncorrelated. Our findings add weight to the proposal that semantic and episodic memory are served by similar dual-process retrieval systems, though the relationship between the two threshold processes needs to be more fully elucidated.     

Attention to the hands disrupts skilled typewriting: The role of vision in producing the disruption

Drawing typists' attention to their hands by asking them to type only letters assigned to the left or the right hand disrupts their performance, slowing the rate of typing and increasing errors. In this article we test the hypothesis that slowing occurs because typists watch their hands to determine which hand types which letter. Skilled typists were cued to type letters of one hand or of both hands while they could view their hands on the keyboard and while their vision was blocked by a box placed over the keyboard. Typing was slower when letters of one hand were typed than when letters of both hands were typed, and the slowing was greater when the hands were covered than when they were not. This supports the hypothesis that slowing occurs because typists watch their hands. However, typists were able to type letters of one hand when the keyboard was covered, so typists must have monitored kinesthetic information as well.     

The accuracy with which adults who do not stutter predict stuttering-related communication attitudes

The purpose of this study was to examine the extent to which adults who do not stutter can predict communication-related attitudes of adults who do stutter. 40 participants (mean age of 22.5 years) evaluated speech samples from an adult with mild stuttering and an adult with severe stuttering via audio-only (n = 20) or audio-visual (n = 20) modes to predict how the adults had responded on the S24 scale of communication attitudes. Participants correctly predicted which speaker had the more favorable S24 score, and the predicted scores were significantly different between the severity conditions. Across the four subgroups, predicted S24 scores differed from actual scores by 4–9 points. Predicted values were greater than the actual values for 3 of 4 subgroups, but still relatively positive in relation to the S24 norm sample. Stimulus presentation mode interacted with stuttering severity to affect prediction accuracy. The participants predicted the speakers’ negative self-attributions more accurately than their positive self-attributions. Findings suggest that adults who do not stutter estimate the communication-related attitudes of specific adults who stutter in a manner that is generally accurate, though, in some conditions, somewhat less favorable than the speaker's actual ratings. At a group level, adults who do not stutter demonstrate the ability to discern minimal versus average levels of attitudinal impact for speakers who stutter. The participants’ complex prediction patterns are discussed in relation to stereotype accuracy and classic views of negative stereotyping.Educational objectives: The reader will be able to (a) summarize main findings on research related to listeners’ attitudes toward people who stutter, (b) describe the extent to which people who do not stutter can predict the communication attitudes of people who do stutter; and (c) discuss how findings from the present study relate to previous findings on stereotypes about people who stutter.     

What exactly interacts with spelling-sound consistency in word naming?

Word frequency, age of acquisition (AoA), and imageability were combined with spelling-sound consistency, and their effects on word naming were examined. Frequency and AoA interacted with consistency (Experiments 1 and 2). Imageability did not (Experiment 3). Experiment 4 replicated Experiment 2 of E. Strain, K. E. Patterson, and M. S. Seidenberg's (1995) study and obtained the same apparent effect of imageability on naming. That effect disappeared when AoA was entered as a covariate. An explanation of the interactions of consistency with frequency and AoA is offered in terms of the properties of adaptive connectionist networks given gradual and cumulative training.     

Working memory, task switching, and executive control in the task span procedure

Four experiments explored the task span procedure: Subjects received lists of 1-10 task names to remember and then lists of 1-10 stimuli on which to perform the tasks. Task span is the number of tasks performed in order perfectly. Experiment 1 compared the task span with the traditional memory span in 6 practiced subjects and found little difference. Experiment 2 compared the task span and the memory span in 64 unpracticed subjects and also found little difference. Experiment 3 compared practice with consistent and varied lists to address retrieval from long-term memory. Experiment 4 manipulated the number of task switches and found that it had little effect on task spans. The results suggest there is no trade-off between storage and task switching, which supports some theories of executive control and challenges others.     

Modality differences in short-term memory for rhythms

Prior research has established that performance in short-term memory tasks using auditory rhythmic stimuli is frequently superior to that in tasks using visual stimuli. In five experiments, the reasons for this were explored further. In a same-different task, pairs of brief rhythms were presented in which each rhythm was visual or auditory, resulting in two same-modality conditions and two cross-modality conditions. Three different rates of presentation were used. The results supported the temporal advantage of the auditory modality in short-term memory, which was quite robust at the quickest presentation rates. This advantage tended to decay as the presentation rate was slowed down, consistent with the view that, with time, the temporal patterns were being recoded into a more generic form.     

Confirmation of an Inhibitory Control Deficit in Attention-Deficit/Hyperactivity Disorder

The objective of this study was to determine whether deficient inhibitory control distinguishes children with a diagnosis of attention-deficit/hyperactivity (ADHD) disorder, conduct disorder (CD), and comorbid ADHD + CD from normally developing children. Participants were rigorously diagnosed children (age 7 to 12 years) with ADHD (N = 72), CD (N = 13) or ADHD + CD (N = 47) and 33 control children (NC). We studied inhibitory control using the stop-signal paradigm, a laboratory task that assessed the ability to inhibit an ongoing action. The ADHD group had significantly impaired inhibitory control compared to NC, CD, and ADHD + CD children. These results indicate that children with ADHD have deficient inhibition as measured in the stop-signal paradigm and that ADHD occurring in the presence of ADHD + CD may represent a phenocopy of CD rather than a variant of ADHD.