Inhibitory effects on response force in the stop-signal paradigm

The forcefulness of key press responses was measured in stop-all and selective stopping versions of the stop-signal paradigm. When stop signals were presented too late for participants to succeed in stopping their responses, response force was nonetheless reduced relative to trials in which no stop signal was presented. This effect shows that peripheral motor aspects of primary task responses can still be influenced by inhibition even when the stop signal arrives too late to prevent the response. It thus requires modification of race models in which responses in the presence of stop signals are either stopped completely or produced normally, depending on whether the responding or stopping process finishes first.     

Response time models of delta plots with negative-going slopes

Delta plots (DPs) graphically compare reaction time (RT) quantiles obtained under two experimental conditions. In some research areas (e.g., Simon effects), decreasing delta plots (nDPs) have consistently been found, indicating that the experimental effect is largest at low quantiles and decreases for higher quantiles. nDPs are unusual and intriguing: They imply that RT in the faster condition is more variable, a pattern predicted by few standard RT models. We describe and analyze five classes of well-established latency mechanisms that are consistent with nDPs--exhaustive processing models, correlated stage models, mixture models, cascade models, and parallel channels models--and discuss the implications of our analyses for the interpretation of DPs. DPs generally do not imply any specific processing model; therefore, it is more fruitful to start from a specific quantitative model and to compare the DP it predicts with empirical data.     

Negative life events and substance use moderate cognitive behavioral adolescent depression prevention intervention

Investigate factors that amplify or mitigate the effects of an indicated cognitive behavioral (CB) depression prevention program for adolescents with elevated depressive symptoms. Using data from a randomized trial (Registration No. NCT00183417; n?=?173) in which adolescents (M age =?15.5, SD =?1.2) were assigned to a brief cognitive behavioral prevention program or an educational brochure control condition, we tested whether elevated motivation to reduce depression and initial depressive symptom severity amplified intervention effects and whether negative life events, social support deficits, and substance use attenuated intervention effects. Hierarchical linear modeling (HLM) indicated differential intervention effects for two of the five examined variables: negative life events and substance use. For adolescents at low and medium levels of substance use or negative life events, the CB intervention produced declines in depressive symptoms relative to controls. However, at high levels of substance use or negative life events, the CB intervention did not significantly reduce depressive symptoms in comparison to controls. Results imply that high-risk adolescents with either high rates of major life stress or initial substance use may require specialized depression prevention efforts.     

Response-level probability effects on reaction time: now you see them, now you don't

Many reaction time (RT) experiments have tested for response-level probability effects. Their results have been mixed, which is surprising because psychophysiological studies provide clear evidence of motor-level changes associated with an anticipated response. A survey of the designs used in the RT studies reveals many potential problems that could conceal the effects of response probability. We report five new RT experiments testing for response-level probability effects with the most promising of the previous designs-that of Blackman ( 1972 )-and with new designs. Some of these experiments yield evidence of response-level probability effects, but others do not. It appears that response-level probability effects are present primarily in simple tasks with a strong emphasis on response preparation, possibly because participants only expend effort on response preparation in these tasks.     

Social representations in the ordinary explanation of a ‘riot’

This paper critically examines the notion of social representations by way of a systematic analysis of media and participants' accounts of the St Pauls street disturbances of 1980. The analysis concentrates on two major explanatory categories which appear in the accounts: (A) ‘race’; (B) ‘government cuts and amenities’. In each case it is possible to distinguish three different levels of consensus between accounts: (i) particular explanatory schemata can be recognized as available but treated as mistaken; (ii) particular explanatory schemata can be recognized as relevant and adopted to explain the particular events, although in different ways; (iii) particular schemata can be adopted and used to explain events in the same way. The flexible meaning of these categories is highlighted along with the recurrent reference to alternative explanations. These findings raise problems for the suggestion that social representations minimize conflict and create ‘consensual universes’, and question the straightforward relationship between social representations and identifiable social groups. In conclusion the need is identified for a more detailed analysis of the language in which social representations are couched, and the relationship they bear to different contexts of use.     

Pictures in sentences: understanding without words

To understand a sentence, the meanings of the words in the sentence must be retrieved and combined. Are these meanings represented within the language system (the lexical hypothesis) or are they represented in a general conceptual system that is not restricted to language (the conceptual hypothesis)? To evaluate these hypotheses, sentences were presented in which a pictured object replaced a word (rebus sentences). Previous research has shown that isolated pictures and words are processed equally rapidly in conceptual tasks, but that pictures are markedly slower than words in tasks requiring lexical access. The lexical hypothesis would therefore lead one to expect that rebus sentences will be relatively difficult, whereas the conceptual hypothesis would predict that rebus sentences would be rather easy. Sentences were shown using rapid serial visual presentation (RSVP) at a rate of 10 or 12 words per second. With one set of materials (Experiments 1 and 2), readers took longer to judge the plausibility of rebus sentences than all-word sentences, although the accuracy of judgment and of recall were similar for the two formats. With two new sets of materials (Experiments 3 and 5), rebus and all-word sentences were virtually equivalent except in one circumstance: when a picture replaced the noun in a familiar phrase such as seedless grapes. In contrast, when the task required overt naming of the rebus picture in a sentence context, latency to name the picture was markedly longer than to name the corresponding word, and the appropriateness of the sentence context affected picture naming but not word naming (Experiment 4). The results fail to support theories that place word meanings in a specialized lexical entry. Instead, the results suggest that the lexical representation of a noun or familiar noun phrase provides a pointer to a nonlinguistic conceptual system, and it is in that system that the meaning of a sentence is constructed.     

Reactions to social vs self-evaluation: Moderating effects of personal and social identity orientations

People differ in the degree to which their identities are based on personal versus social identity characteristics. This experiment tested the hypothesis that people are most concerned about evaluations that are relevant to their salient identity orientation. The Aspects of Identity Questionnaire was used to classify subjects as low or high in personal and social identities. Subjects then anticipated taking a test, believing that their performance would be known by only them, by only a research assistant, by both them and a research assistant, or by no one. Subjects then completed thought-listing and self-report measures of evaluation apprehension. Subjects who scored high in social identity reacted more strongly to the social evaluation than subjects low in social identity. Although subjects high in personal identity were not particularly threatened by private feedback, personal identity seemed to buffer subjects against the threat of social-evaluation. The results are discussed in the context of recent work on private and public aspects of the self.