Automatic semantic activation is no myth: semantic context effects on the N400 in the letter-search task in the absence of response time effects

The claim that semantic activation is an automatic process was recently called a myth, on the basis of the finding that if letter search is performed on a prime word, semantic priming effects on response time are eliminated, whereas repetition effects are preserved. The absence of semantic activation, however, cannot be validly inferred from the lack of response time effects, and converging evidence is needed. To this end, we examined the event-related potential correlate of priming, the N400 amplitude modulation, in a letter-search priming paradigm. Our experiment replicated the response time effects and demonstrated that the N400 amplitude successfully differentiates cross-case repetition priming, semantic priming, and neutral conditions. The results clearly indicate that the meaning of the prime word was processed and that semantic activation indeed was present in the letter-search task. The notion that semantic activation is an automatic process should not be abandoned prematurely.     

What happens next? The predictability of natural behaviour viewed through CCTV cameras

Can potentially antisocial or criminal behaviour be predicted? Our study aimed to ascertain (a) whether observers can successfully predict the onset of such behaviour when viewing real recordings from CCTV; (b) where, in the sequence of events, it is possible to make this prediction; and (c) whether there may be a difference between na?ve and professional observers. We used 100 sample scenes from UK urban locations. Of these, 18 led to criminal behaviour (fights or vandalism). A further 18 scenes were matched as closely as possible to the crime examples, but did not lead to any crime, and 64 were neutral scenes chosen from a wide variety of noncriminal situations. A signal-detection paradigm was used in conjunction with a 6-point rating scale. Data from fifty na?ve and fifty professional observers suggest that (a) observers can distinguish crime sequences from neutral sequences and from matches; (b) there are key types of behaviour (particularly gestures and body position) that allow predictions to be made; (c) the performance of na?ve observers is comparable to that of experts. However, because the experts were predominantly male, the absence of an effect of experience may have been due to gender differences, which were investigated in a subsidiary experiment. The results of experiment 2 leave open the possibility that females perform better than males at such tasks.     

Aging and the perception of depth and 3-D shape from motion parallax

The ability of younger and older observers to perceive 3-D shape and depth from motion parallax was investigated. In Experiment 1, the observers discriminated among differently curved 3-dimensional (3-D) surfaces in the presence of noise. In Experiment 2, the surfaces' shape was held constant and the amount of front-to-back depth was varied; the observers estimated the amount of depth they perceived. The effects of age were strongly task dependent. The younger observers' performance in Experiment 1 was almost 60% higher than that of the older observers. In contrast, no age effect was obtained in Experiment 2. Older observers can effectively perceive variations in depth from patterns of motion parallax, but their ability to discriminate 3-D shape is significantly compromised.     

Modularity and spatial reorientation in a simple mind: encoding of geometric and nongeometric properties of a spatial environment by fish

When disoriented in environments with distinctive geometry, such as a closed rectangular arena, human infants and adult rats reorient in accord with the large-scale shape of the environment, but not in accord with nongeometric properties such as the colour of a wall. Human adults, however, conjoined geometric and nongeometric information to reorient themselves, which has led to the suggestion that spatial processing tends to become more flexible over development and evolution. We here show that fish tested in the same tasks perform like human adults and surpass rats and human infants. These findings suggest that the ability to make use of geometry for spatial reorientation is an ancient evolutionary tract and that flexibility and accessibility to multiple sources of information to reorient in space is more a matter of ecological adaptations than phylogenetic distance from humans.     

Evidence for frequency-based constituents in the mental lexicon: collocations involving the word of

In this paper, it is hypothesized that units larger than the traditional word, such as two-word collocations and phrases, may be stored in the mental lexicon and accessed holistically. Following previously published work on the Network or Usage-based model of lexical storage (Bybee, 1985, 1995), we suggest that the mechanism determining this constituency is the frequency with which items occur together in natural, connected speech: the collocational frequency. The present study uses a word-monitoring paradigm to investigate reaction times to the English function word of in collocations of varying levels of frequency. A significant effect of collocational frequency was observed; response latencies were longer when the target word of occurred in the very frequent collocations, indicating holistic processing of the frequent phrases. Furthermore, response latencies presented here are considerably longer than those reported in previous studies. This is explained as a result of the hypothesized holistic representation as well as a function of the use of stimuli extracted from natural conversation.     

Correlates of exercise adherence in an African American church community

This study identified correlates of attendance to a community-based exercise program in an African American church congregation. After medical clearance, 48 participants completed measures of social support, health-related quality of life, depression, exercise self-efficacy, and exercise motivation and then participated in an exercise program for 6 months (attendance rate = 27%). Age, a sense of affiliation as a motivator to exercise, and weekly caloric expenditure derived from yard work were positively associated with program attendance, and full- or part-time employment was negatively associated with attendance. The authors concluded that exercise adherence is a complicated phenomenon that is influenced by a variety of environmental, personal, and social factors. Social factors, in particular, may be important in promoting adherence to an exercise program in African Americans.     

Effects of fimbria lesions on trace two-way active avoidance acquisition and retention in rats

The fimbria-fornix (FF) is the main subcortical input to the hippocampus. It has been shown that FF lesions facilitate performance on a standard-delay two-way active avoidance task (AA2), thought to involve implicit memory. The hippocampal region is required for explicit or relational memory. It has been proposed that the hippocampus and related structures might associate events that are separated in space or time and detect elements shared in common by such discontiguous episodes. Therefore, FF lesions would be expected to impair performance on a trace paradigm, which introduces an interval between the CS (conditioned stimulus) and the US (unconditioned stimulus) and is generally considered a model of explicit memory. We predicted that FF lesions would impair memory in a trace AA2 procedure, while the same lesions would facilitate memory in a standard delay version of the task. To test this hypothesis, two experiments were carried out in 102 male Wistar rats. The first experiment characterized the trace paradigm using this kind of conditioning and demonstrated that control rats were able to acquire and retrieve (24 h and 11 days postacquisition) the association between the CS (tone) and the US (electric foot shock) when a trace interval (5, 10, or 20 s) was interposed between both stimuli. In the second experiment, we investigated the effects of FF electrolytic lesions on the same task using delay and trace (10-s trace interval) paradigms. Surprisingly, FF lesions facilitated the acquisition and the 24-h retention of the AA2 not only on the standard delay paradigm, but also with the trace paradigm. We suggest that facilitative effects could be a result of impairment in contextual learning.