Exhausting attentional tracking resources with a single fast-moving object

Driving on a busy road, eluding a group of predators, or playing a team sport involves keeping track of multiple moving objects. In typical laboratory tasks, the number of visual targets that humans can track is about four. Three types of theories have been advanced to explain this limit. The fixed-limit theory posits a set number of attentional pointers available to follow objects. Spatial interference theory proposes that when targets are near each other, their attentional spotlights mutually interfere. Resource theory asserts that a limited resource is divided among targets, and performance reflects the amount available per target. Utilising widely separated objects to avoid spatial interference, the present experiments validated the predictions of resource theory. The fastest target speed at which two targets could be tracked was much slower than the fastest speed at which one target could be tracked. This speed limit for tracking two targets was approximately that predicted if at high speeds, only a single target could be tracked. This result cannot be accommodated by the fixed-limit or interference theories. Evidently a fast target, if it moves fast enough, can exhaust attentional resources.     

Multiple goals, writing strategies, and written outcomes for college students learning English as a second language

This study examined relations of achievement goals of writers who are speakers of English as a foreign language (EFL), the frequency of their writing strategy use, and the quality of their writing from a multiple goals perspective. The goal profiles of 57 EFL college students with similar writing proficiency were based on rating items of an unpublished scale; Group 1 had strong mastery and strong performance-approach goals, and two groups included students with only one strong mastery (Group 2) or performance (Group 3) goal. Think-aloud protocols indicated that the participants adopted 21 strategies in an argumentative writing task, classified into five categories. Group 1 was found to use writing strategies of monitoring or evaluating, revising, and compensating significantly more often than the other two groups, and produced better essays. Strong mastery and performance-approach goals might be beneficial for EFL college writers.     

The evolution of decision-making under risk: Framing effects in monkey risk preferences

When making choices between risky options, human decision-makers exhibit a number of framing effects. One of the most prominent framing effects is the tendency for decision makers to evaluate gambles relative to a reference point, and to act risk-seeking when prospects are framed as losses but risk-averse when identical prospects are framed as gains. This tendency for risk-preferences to reverse between loss and gain frames has been termed the reflection effect, and is one of the primary predictions of Prospect Theory. Here, we explore whether non-human primates exhibit a similar reflection effect. Using a token-trading task, we show that capuchin monkeys (Cebus apella) exhibit an analogous reversal of risk preferences depending on whether outcomes are presented as gains or losses, suggesting that similar framing effects also influence choice in non-human primates. This finding suggests that the mechanisms that drive framing effects in humans may be evolutionarily ancient, extending broadly across the primate order.     

Modulation of N400 in chronic non-fluent aphasia using low frequency Repetitive Transcranial Magnetic Stimulation (rTMS)

Low frequency Repetitive Transcranial Magnetic Stimulation (rTMS) has previously been applied to language homologues in non-fluent populations of persons with aphasia yielding significant improvements in behavioral language function up to 43 months post stimulation. The present study aimed to investigate the electrophysiological correlates associated with the application of rTMS through measurement of the semantic based N400 Event-related brain potentials (ERP) component. Low frequency (1 Hz) rTMS was applied to the anterior portion of the homologue to Broca’s area (pars triangularis), for 20 min per day for 10 days, using a stereotactic neuronavigational system. Twelve non-fluent persons with aphasia, 2-6 years post stroke were stimulated. Six participants were randomly assigned to receive real stimulation and six participants were randomly assigned to receive a blind sham control condition. ERP measures were recorded at baseline, 1 week and 2 months subsequent to stimulation. The findings demonstrate treatment related changes observed in the stimulation group when compared to the placebo control group at 2 months post stimulation indicating neuromodulation of N400 as a result of rTMS. No treatment related changes were identified in the stimulation group, when compared to the sham group from baseline to 1 week post stimulation. The electrophysiological results represent the capacity of rTMS to modulate neural language networks and measures of lexical-semantic function in participants with non-fluent aphasia and suggest that time may be an important factor in brain reorganization subsequent to rTMS.     

Adolescent political activism and long-term happiness: a 21-year longitudinal study on the development of micro- and macrosocial worries

Utilizing latent growth modeling, the long-term development of worries among peace movement supporters is examined. Data originate from a seven-wave German longitudinal study started in 1985 with on average 14-year-olds. Waves were interspersed 3 and a half years each. Activists are assumed to have lower (self-related) microworries (Hypothesis 1) and higher macroworries (concerned with larger entities; Hypothesis 2) than nonactivists at the onset of the study. Nonactivists who appraised the threat of nuclear war as high in 1985 are assumed to report worse mental health than their activist age-mates 21 years later (Hypothesis 3). Activists are assumed to express relatively more macroworries than nonactivists in midadulthood (Hypothesis 4). All four hypotheses were confirmed. Results are interpreted in a stress-coping (Lazarus) and resource (Elder) framework, suggesting that refraining from acting out against a perceived sociopolitical threat is a long-term risk for a positive mental health trajectory.     

Cognitive impairment and whole brain diffusion in patients with neuromyelitis optica after acute relapse

The objective of this study investigated cognitive impairments and their correlations with fractional anisotropy (FA) and mean diffusivity (MD) in patients with neuromyelitis optica (NMO) without visible lesions on conventional brain MRI during acute relapse. Twenty one patients with NMO and 21 normal control subjects received several cognitive tests to assess cognitive function. Head diffusion tensor imaging (DTI) of all patients with NMO were collected with a 3-T MR system. Correlations of cognitive test scores and whole brain FA and MD were examined by voxel-based analysis. Region-of-interest analysis was applied to the significantly correlated regions which the most frequently appeared. We found that NMO patients without visible brain lesions had significantly impaired learning and memory, decreased information processing speed, and damaged attention compared with normal control subjects. These impaired cognitive domains were significantly correlated with FA and MD in local regions of corpus callosum, anterior cingulate and medial frontal cortex. In corpus callosum of NMO patients, mean FA was significantly lower and mean MD higher than normal control subjects. Our findings suggest that cognitive impairments in learning and memory, information processing speed and attention occur in NMO patients without visible brain lesions during acute relapse. The impairments in immediate and short-term memory in NMO patients may be due to information encoding deficits in the process of information acquisition. The corpus callosum of such patients may have local microscopic damages that play a role in cognitive impairments during acute relapse.     

Activation of morphemic meanings in processing opaque words

Two masked priming experiments were conducted to examine the activation of morphemic forms and meanings during opaque word processing. In Experiment 1, opaque primes significantly facilitated the recognition of transparent targets, which was consistent with previous results. However, transparent primes did not influence the recognition of opaque targets. This asymmetry could not be explained solely by morpho-orthographic processing, but it was consistent with models that have assumed early morpho-semantic activation. Experiment 2 directly tested whether the meanings of the constituent morphemes in opaque words were activated. In the critical condition, the targets were unrelated to the opaque primes at the lexical level, but were semantically related to their morphemes (e.g., “butterfly–bread”). Facilitation was observed in this condition, providing strong evidence of morpho-semantic activation during opaque-word recognition. These findings indicate that although initial morphological decomposition is determined by surface morphological form, it does not necessarily imply that morphemic meanings will be activated at later stages of processing. Rather, the morphemic meanings may be available automatically once segmentation is complete.     

Conceptual response distance and intervening keys distinguish action goals in the Stroop color-identification task

In previous studies, a physical response-distance effect was found in the two-choice Stroop color-identification task, with the Stroop effect being larger when the two response keys were physically close together than when they were far apart. In the present study, we found a conceptual response-distance effect, with the Stroop effect being larger when the response keys were conceptually close (labeled as “5” and “6”) than when they were conceptually far (labeled as “1” and “9”). Moreover, a response-distance effect due to pure physical distance was not evident; rather, the effect was found only when additional keys were placed between the two far response keys. These results are in agreement with a view that response keys are coded as action goals, with farther conceptual distance and additional keys helping distinguish the action goals. The results are difficult to reconcile with accounts that place emphasis on the physical separation of the effectors or their inanimate extensions.