Processing visual words with numbers: Electrophysiological evidence for semantic activation

Perea, Duñabeitia, and Carreiras (Journal of Experimental Psychology: Human Perception and Performance 34:237–241, 2008) found that LEET stimuli, formed by a mixture of digits and letters (e.g., T4BL3 instead of TABLE), produced priming effects similar to those for regular words. This finding led them to conclude that LEET stimuli automatically activate lexical information. In the present study, we examined whether semantic activation occurs for LEET stimuli by using an electrophysiological measure called the N400 effect. The N400 effect, also known as the mismatch negativity, reflects detection of a mismatch between a word and the current semantic context. This N400 effect could occur only if the LEET stimulus had been identified and processed semantically. Participants determined whether a stimulus (word or LEET) was related to a given category (e.g., APPLE or 4PPL3 belongs to the category “fruit,” but TABLE or T4BL3 does not). We found that LEET stimuli produced an N400 effect similar in magnitude to that for regular uppercase words, suggesting that LEET stimuli can access meaning in a manner similar to words presented in consistent uppercase letters.     

Reorganization in coping behavior at 1 1/2 years: dynamic systems and normative change

By the age of 1 year toddlers demonstrate distinct coping habits for dealing with frustration. However, these habits may be open to change and reorganization at subsequent developmental junctures. We investigated change in coping habits at 18-20 months, a normative age for major advances in social cognition, focusing on the dynamic systems principles of fluctuation and novelty at transitions. Specifically, we asked whether month-to-month fluctuation, novel behavioral habits and real-time variability increased at the age of a normative transition, despite individual differences in the content of behavior. Infants were given frustrating toys while their mothers sat nearby without helping, on monthly visits at 14-25 months (before, during and after the hypothesized transition). State space grids representing patterns of behavioral durations were constructed for each episode and compared over age. As predicted, month-to-month fluctuation in grid patterns increased temporarily between 17 and 20 months, partly independently of a concurrent peak in distress, and new behavioral habits replaced old ones at the same age. Coping habits changed differently for high-and low-distressed toddlers. However, changes in real-time variability did not generally meet our expectations.     

On the limits of advance preparation for a task switch: do people prepare all the task some of the time or some of the task all the time?

This study investigated the nature of advance preparation for a task switch, testing 2 key assumptions of R. De Jong's (2000) failure-to-engage theory: (a) Task-switch preparation is all-or-none, and (b) preparation failures stem from nonutilization of available control capabilities. In 3 experiments, switch costs varied dramatically across individual stimulus-response (S-R) pairs of the tasks-virtually absent for 1 pair but large for others. These findings indicate that, across trials, task preparation was not all-or-none but, rather, consistently partial (full preparation for some S-R pairs but not others). In other words, people do not prepare all of the task some of the time, they prepare some of the task all of the time. Experiments 2 and 3 produced substantial switch costs even though time deadlines provided strong incentives for optimal advance preparation. Thus, there was no evidence that people have a latent capability to fully prepare for a task switch.     

Dual-task performance with ideomotor-compatible tasks: is the central processing bottleneck intact, bypassed, or shifted in locus?

The present study examined whether the central bottleneck, assumed to be primarily responsible for the psychological refractory period (PRP) effect, is intact, bypassed, or shifted in locus with ideomotor (IM)-compatible tasks. In 4 experiments, factorial combinations of IM- and non-IM-compatible tasks were used for Task 1 and Task 2. All experiments showed substantial PRP effects, with a strong dependency between Task 1 and Task 2 response times. These findings, along with model-based simulations, indicate that the processing bottleneck was not bypassed, even with two IM-compatible tasks. Nevertheless, systematic changes in the PRP and correspondence effects across experiments suggest that IM compatibility shifted the locus of the bottleneck. The findings favor an engage-bottleneck-later hypothesis, whereby parallelism between tasks occurs deeper into the processing stream for IM- than for non-IM-compatible tasks, without the bottleneck being actually eliminated.     

Nonautomatic emotion perception in a dual-task situation

Are emotions perceived automatically? Two psychological refractory period experiments were conducted to ascertain whether emotion perception requires central attentional resources. Task 1 required an auditory discrimination (tone vs. noise), whereas Task 2 required a discrimination between happy and angry faces. The difficulty of Task 2 was manipulated by varying the degree of emotional expression. The stimulus onset asynchrony (SOA) between Task 1 and Task 2 was also varied. Experiment 1 revealed additive effects of SOA and Task 2 emotion-perception difficulty. Experiment 2 replicated the additive relationship with a stronger manipulation of emotion-perception difficulty. According to locus-of-slack logic, our participants did not process emotional expressions while central resources were devoted to Task 1. We conclude that emotion perception is not fully automatic.     

Age-related emotional bias in processing two emotionally valenced tasks

Psychological Research - Previous studies suggest that older adults process positive emotions more efficiently than negative emotions, whereas younger adults show the reverse effect. We examined...     

On the nonautomaticity of visual word processing: electrophysiological evidence that word processing requires central attention

The present study used event-related potentials (ERPs) to determine the degree to which people can process words while devoting central attention to another task. Experiments 1-4 measured the N400 effect, which is sensitive to the degree of mismatch between a word and the current semantic context. Experiment 5 measured the P3 difference between low- and high-frequency words. Because these effects can occur only if a word has been identified, both ERP components index word processing. The authors found that the N400 effect (Experiments 1, 3, and 4) and the P3 difference (Experiment 5) were strongly attenuated for Task 2 words presented nearly simultaneously with Task 1. No such attenuation was found when the Task 1 stimulus was presented but required no response (Experiment 2). Strong attenuation was also evident when the Task 2 word was presented before the Task 1 stimulus (Experiment 4), suggesting that central resources are not allocated to stimuli first-come, first-served but rather are strategically locked to Task 1. The authors conclude that visual word processing is not fully automatic but rather requires access to limited central attentional resources.     

Inhibition of task set: Converging evidence from task choice in the voluntary task-switching paradigm

This study looked for evidence of task-set inhibition in a voluntary task-switching paradigm. Participants performed one of three tasks on a digit: parity (even or odd), size (less than or greater than 5), or distance (near or far from 5). On each trial, they were allowed to choose which task to perform, with encouragement to perform each task equally often overall and in a random sequence. The question was whether participants would avoid performing a task that they had recently switched away from (e.g., the task performed on trial n22), because the task set was still inhibited. Results confirmed that participants strongly avoided performing the n22 task (e.g., ABA) in favor of performing other tasks (e.g., ABC). This occurred both when participants were required to switch tasks every trial (Experiment 1) and when they were allowed to repeat tasks (Experiment 2). The results suggest that a task set is inhibited during switching to a new task, reducing the likelihood that this task will be selected in the near future.