Does spreading activation summate?

Summary Network models of semantic memory assume implicitly or explicitly that the degree of activation of a node is a monotonic function of the total amount of excitation reaching that node from all sources. For example, the activation level of the node representing apple should be greater if it is receiving excitation due to the activation of the nodes for fruit and pear than if only one of these neighboring nodes is activated. This notion was tested by presenting semantic primes 80 ms or 320 ms before a letter string (e.g., apple or ipple) requiring a lexical decision. The prime stimuli consisted of a pair of simultaneous items that were identical in the single prime condition (e.g., fruit/fruit or pear/pear) or different in the double prime condition (e.g., fruit/pear or pear/fruit), and were either related (target = apple) or unrelated (target = copper) to the target, or neutral. As predicted by the summation of semantic activation assumption of network models there was a larger priming effect (in the 320 ms SOA condition) following the simultaneous activation of two related nodes than following the activation of only one node.This research was supported by grants to the first author from the Natural Sciences and Engineering Research Council of Canada.     

Letter identification declines with increasing retinal eccentricity at the same rate for normal and dyslexic readers

It has recently been claimed (Geiger & Lettvin, 1987; Perry, Dember, Warm, & Sacks, 1989) that the acuity/eccentricity function is flatter in dyslexics than in normal subjects, with dyslexics showing better performance in the periphery and worse performance at fixation. In these studies, all target letters were presented to the right of fixation, a procedural flaw inviting subjects to optimize performance by directing attention and/or gaze to the right of the designated fixation point. It is suggested that dyslexic and normal readers may differ in the degree to which they might adopt the optimal strategy in this situation. To overcome this problem, target letters were briefly presented at 16 randomly intermixed locations derived from the orthogonal combination of four eccentricities and four directions from fixation (above, below, right, left). The accuracy of letter identification declined with increasing eccentricity at the same rate for good and poor adult readers and dyslexic teenagers. This finding provides no support for the view that the acuity/eccentricity function might vary with and possibly cause differences in reading level.     

Enhancement of auditory fear conditioning after housing in a complex environment is attenuated by prior treatment with amphetamine

Prior exposure to drugs of abuse has been shown to occlude the structural plasticity associated with living in a complex environment. Amphetamine treatment may also occlude some cognitive advantages normally associated with living in a complex environment. To test this hypothesis we examined the influence of prior exposure to amphetamine on fear conditioning in rats housed in either a standard or complex environment. Housing in a complex environment facilitated fear learning to an auditory conditioned stimulus (CS), but not to the training context, relative to animals housed singly or in a social group. Prior treatment with amphetamine eliminated this effect. These results indicate that living in a complex environment facilitates conditional freezing to an auditory CS, and that this effect is abolished by pretreatment with amphetamine.     

THE SECOND SPHERE AND THE STORY OF NO STORY

The author discusses Roy Schafer's ideas of the second self and second reality, as well as his consistent theme of storyteller and story. The latter theme is also explored in the context of more recent psychoanalytic influences, such as Bionian thought, trauma theory, the French approach, and the interpersonal perspective. To illustrate the idea of the nonstory in today's clinical encounters, the author presents two clinical vignettes.     

Counselor Competency in the Courtroom

This article outlines general courtroom procedures and offers systematic practical advice for the counselor testifying as an expert witness. Major topics include the counselor role in court, preparing for testimony, answering questions, and dealing with the cross-examination.     

Strategic factors in a lexical-decision task: Evidence for automatic and attention-driven processes

The present study examined strategic factors in a semantic-priming, lexical-decision task. The first experiment demonstrated that the greater the proportion of related word-word pairs to unrelated word-word pairs, the greater the amount of facilitation, a result which is consistent with others reported in the literature. The second experiment demonstrated that this strategic factor apparently requires that sufficient time (at least several hundred milliseconds) be available for the processing of the priming word, and thus is probably caused by attention-driven processes. The third experiment replicated and extended the results of the first two studies by demonstrating that prime-target stimulus onset asynchrony is an important limiting factor in determining whether such proportion-induced strategic factors are involved in word-recognition processes, even when no other aspect or variable of the procedure changes. The results are discussed in the context of Posner and Snyder’s (1975a) two-process model of word recognition.     

Automatic and strategic effects in semantic priming: An examination of Becker’s verification model

Becker’s (1980) verification model, in conjunction with a two-strategy hypothesis, is cited as an alternative to a dual-process model (e.g., Posner & Snyder, 1975) of word recognition and semantic priming. Becket’s approach suggests that individuals can use either an “expectancy” or a “prediction” strategy in word recognition, and maintains that the verification model successfully predicts certain patterns of facilitation and inhibition in a semantic priming task that a dual-process model cannot. The present study demonstrated that when a long stimulus-onset asynchrony (SOA = 1,000 msec) is used between prime and target, support is given to Becker’s findings, and to the verification model approach. However, at a short SOA (200 msec), no evidence is found for the hypothesized difference between strategic processes. The results are consistent with other findings (e.g., Neely, 1977) in showing that strategic factors in semantic priming are largely inoperative at short prime-target SOAs, and suggests that Becker’s model is not general enough to rule out some type of dual-process model.