Sex differences in the lateralized processing of facial emotion

Two reaction time tasks were administered to male and female normal subjects, involving judgments of facial emotion. In the Word-Face task, judgments of similarity or difference of a centrally presented emotion word and an emotional face presented in the left or right visual field were required, and in the Face-Face task, comparisons of a centrally presented and a laterally presented emotional face were required. Results were significant for the matching trials only. Reaction times to negative emotions were faster overall than to positive emotions, and an Emotional Valence by Visual Field interaction was found such that reaction times were faster for negative emotions in the left visual field and for positive emotions in the right visual field. This interaction was significant for the female but not the male subjects, although similar patterns were observed in both sexes. Further, an interaction of Gender, Task, and Emotional Valence was found, such that the two tasks had opposite effects for the two sexes. The Face-Face task appeared to inhibit the performance of the male subjects and facilitate the performance of the female subjects in terms of reaction time. It was suggested that specifying the target emotion by an emotional face elicits a greater emotional response on the part of the subject than specification by a word, and that this emotional elicitation may result in a reactive inhibition in the male subjects and in an elaboration of the emotional response in the female subjects.     

Semantic satiation affects category membership decision time but not lexical priming

Experiments 1 and 2 examined the effects of semantic satiation on category membership decision latency. Subjects overtly repeated the name of a category either 3 or 30 times, and then decided whether or not a target exemplar was a member of the repeated category. Experiment 1 obtained some evidence that member decisions are slower and nonmember decisions are faster following 30 repetitions, but only the interaction was reliable. Experiment 2 confirmed only that member decisions are slower following satiation of the category name. The results support the hypothesis that prolonged repetition of a word reduces the availability of semantic information related to that word. Experiment 3 showed that the magnitude of priming in the lexical decision task is unaffected by satiation of the prime. Several general approaches to understanding semantic satiation are discussed. The most parsimonious account assumes that satiation affects the links or pathways connecting concepts in the satiated category. The net effect is to decrease the rate of search and associative spread of activation in conceptual structures.     

Interhemispheric cooperation and non-cooperation during word recognition: evidence for callosal transfer dysfunction in dyslexic adults

Participants report briefly-presented words more accurately when two copies are presented, one in the left visual field (LVF) and another in the right visual field (RVF), than when only a single copy is presented. This effect is known as the 'redundant bilateral advantage' and has been interpreted as evidence for interhemispheric cooperation. We investigated the redundant bilateral advantage in dyslexic adults and matched controls as a means of assessing communication between the hemispheres in dyslexia. Consistent with previous research, normal adult readers in Experiment 1 showed significantly higher accuracy on a word report task when identical word stimuli were presented bilaterally, compared to unilateral RVF or LVF presentation. Dyslexics, however, did not show the bilateral advantage. In Experiment 2, words were presented above fixation, below fixation or in both positions. In this experiment both dyslexics and controls benefited from the redundant presentation. Experiment 3 combined whole words in one visual field with word fragments in the other visual field (the initial and final letters separated by spaces). Controls showed a bilateral advantage but dyslexics did not. In Experiments 1 and 3, the dyslexics showed significantly lower accuracy for LVF trials than controls, but the groups did not differ for RVF trials. The findings suggest that dyslexics have a problem of interhemispheric integration and not a general problem of processing two lexical inputs simultaneously.     

The locus of semantic satiation in category membership decision and acceptability judgment

The locus of semantic satiation was investigated in three experiments. In Experiments 1 and 2 subjects performed a category membership decision task following the repetition (3 or 30 times) of the category name. In order to distinguish the effect of semantic satiation from the possible effect of repetition on the identification of the member word, two measures were recorded, namely (a) the member word reading time and (b) response time. A semantic satiation effect was observed on response times in Experiment 1. No satiation effect was observed, however, when, instead of repeating a single word, the subject had to repeat several words corresponding to a category definition. A facilitation effect due to repetition was observed instead (Experiment 2). An inhibition effect was observed again in Experiment 3 with an acceptability judgment task performed on a short sentence. This pattern of results is consistent with the general hypothesis that semantic satiation is linked to the processes involved in accessing the meaning of the repeated word after the repetition is completed.     

Sequential effects in the lexical decision task: The role of the item frequency of the previous trial

Two lexical decision experiments were conducted to determine whether there is a specific, localized influence of the item frequency of consecutive trials (i.e., first-order sequential effects) when the trials are not related to each other. Both low-frequency words and nonwords were influenced by the frequency of the precursor word (Experiment 1). In contrast, high-frequency words showed little sensitivity to the frequency of the precursor word (Experiment 2), although they showed longer reaction times for word trials preceded by a nonword trial. The presence of sequential effects in the lexical decision task suggests that participants shift their response criteria on a trial-by-trial basis.     

What is learned about nontarget items in simple visual search?

Human sensitivity to correlational structure between nontargets and likelihood of target presence in a visual letter-search task were studied in two experiments. In each of these experiments, the performance of subjects for whom the nontarget information was altered in the final trial block was compared with the performance of subjects for whom the nontarget information did not change. When stimulus strings were presented individually on a computer screen and subjects were required to make a yes-no decision about target presence (Experiment 1), the change in nontarget structure resulted in increased reaction times for target-absent trials. When subjects searched simultaneously for three possible targets (Experiment 2), the change in nontarget structure produced increased error rates and increased reaction times for both target-absent and target-present trials. Correlations between the amount of predictive information in individual stimulus strings and reaction times also showed that both switching and nonswitching subjects were sensitive to the nontarget context. However, neither self-reports of strategy nor postexperiment choices between context-consistent and -inconsistent letter strings indicated any explicit knowledge of the predictive information in the nontarget stimuli. Subjects can thus acquire and benefit from, apparently without awareness, information about subtle correlational structure in nontarget elements in simple visual search.     

Testing an associative account of semantic satiation

How is the meaning of a word retrieved without interference from recently viewed words? The ROUSE theory of priming assumes a discounting process to reduce source confusion between subsequently presented words. As applied to semantic satiation, this theory predicted a loss of association between the lexical item and meaning. Four experiments tested this explanation in a speeded category-matching task. All experiments used lists of 20 trials that presented a cue word for 1 s followed by a target word. Randomly mixed across the list, 10 trials used cues drawn from the same category whereas the other 10 trials used cues from 10 other categories. In Experiments 1a and 1b, the cues were repeated category labels (FRUIT–APPLE) and responses gradually slowed for the repeated category. In Experiment 2, the cues were nonrepeated exemplars (PEAR–APPLE) and responses remained faster for the repeated category. In Experiment 3, the cues were repeated exemplars in a word matching task (APPLE–APPLE) and responses again remained faster for the repeated category.     

Test anxiety and reaction time for matching decisions

Subjects selected by test-anxiety level were presented pairs of words and asked to make judgments of physical identity, acoustic matching, or taxonomic category membership. Experiment 1 varied type of judgment between subjects; in Experiments 2 and 3, each subject made all three decisions. There was no consistent support for the hypothesis that, relative to low-anxiety subjects, high-anxiety subjects would show a more pronounced decrement in reaction times for semantic decisions than for nonsemantic decisions.     

Hemisphere-specific resource demands of task expectancies

The hemisphere-specific resource demands of expecting letter- and figure-matching tasks were investigated, using dual-task methodology. Matching task expectancies were induced by blocking trials with respect to stimulus type (letters or geometrical figures). On one third of the trials, the matching stimuli were unexpectedly omitted. The secondary task required a speeded reaction to a laterally presented auditory probe. The side of probe presentation was unpredictable. Probe reaction times were taken as an index of the resource demands imposed by the primary task on the contralateral hemisphere. For both the trials with and without matching stimuli, probe reaction times showed a significant interaction between lateral side of probe presentation and block type (letters or figures). When letters were expected, reaction times were slower in the left-hemisphere probe task. Probe reaction times were equally fast for both sides when figures were expected. Overall, these results indicate that task expectancies primarily demand resources from the hemisphere that is specialized for carrying out the expected task.     

The basis of the 3/4 view advantage in face recognition

Three-quarter views of faces promote better recognition memory for previously unfamiliar faces than do full-face views. This paper reports experiments which examine the possible basis of the effect, and, in particular, examine whether the effect reflects some ‘canonical’ role for the 3/4 view of a face. Experiment 1 showed no advantage of 3/4 views over full-face views when the task was to decide whether or not each of a series of faces was that of a highly familiar colleague. In Experiment 2 a sequential matching task was used, where subjects had to respond positively if both members of a pair of faces were of the same person. When the faces used were highly familiar to the subjects, there was no evidence of an advantage for a 3/4 view in the matching task. Three-quarter views and full-face views led to equivalent performance, though profiles produced decrements in performance. When the same faces were shown to subjects who were unfamiliar with the faces, 3/4 views did lead to increased speeds in same trials, compared with full-face, though profiles again proved difficult. Thus a 3/4 view advantage appeared only where the faces were unfamiliar, and the task had to be performed at the level of visual matching. It appears that the 3/4 view advantage may be obtained only when the task involves explicit matching between test views and remembered target photographs, rather than reflecting any more fundamental properties of the representations used to recognize highly familiar faces.     

Hemisphere differences in conscious and unconscious word reading

Hemisphere differences in word reading were examined using explicit and implicit processing measures. In an inclusion task, which indexes both conscious (explicit) and unconscious (implicit) word reading processes, participants were briefly presented with a word in either the right or the left visual field and were asked to use this word to complete a three-letter word stem. In an exclusion task, which estimates unconscious word reading, participants completed the word stem with any word other than the prime word. Experiment 1 showed that words presented to either visual field were processed in very similar ways in both tasks, with the exception that words in the right visual field (left hemisphere) were more readily accessible for conscious report. Experiment 2 indicated that unconsciously processed words are shared between the hemispheres, as similar results were obtained when either the same or the opposite visual field received the word stem. Experiment 3 demonstrated that this sharing between hemispheres is cortically mediated by testing a split-brain patient. These results suggest that the left hemisphere advantage for word reading holds only for explicit measures; unconscious word reading is much more balanced between the hemispheres.     

Block‐wise conflict adaptation of visual selectivity: Role of hemisphere‐dependent and location‐specific mechanisms

Three experiments investigated views on modulation of visual selectivity that involve hemisphere‐dependence and conflict frequency based views for a whole display. In each experiment, 16 participants completed a flanker task with compatible/incompatible stimulus arrays presented in the left, center, or right visual fields. The relative frequency of the compatible stimulus‐arrays within a trial block was varied as a function of the visual field. In Experiment 1, the relative compatibility frequency in the lateral visual fields was varied (75% / 25%) but not in the center visual field (50%). The results showed that in the lateral visual fields, the performance between the compatible and incompatible trials differed more in conditions with few (vs. many) compatibility trials. Experiments 2 and 3 validated these findings. In Experiment 2, the compatibility frequency varied in the center visual field but not in the lateral fields, resulting in performance effects in all three visual fields. Experiment 3 varied the magnitude of the differences between the compatibility and incompatibility frequencies. Together, the findings showed that participants adjusted to the frequencies of compatible stimuli in all visual fields, indicating conflict adaptation that depends on the relative frequencies of compatible stimuli. The results also suggest that this adaptation is associated with hemisphere‐dependent and location‐specific mechanisms.     

On the bilingual advantage in conflict processing: Now you see it, now you don’t

We report two experiments exploring more in detail the bilingual advantage in conflict resolution tasks. In particular, we focus on the origin of the bilingual advantage on overall reaction times in the flanker task. Bilingual and monolingual participants were asked to perform a flanker task under different task versions. In Experiment 1, we used two low-monitoring versions where most of the trials were of just one type (either congruent or incongruent). In Experiment 2, we used two high-monitoring versions where congruent and incongruent trials were more evenly distributed. An effect of bilingualism in overall reaction times was only present in the high-monitoring condition. These results reveal that when the task at hand recruits a good deal of monitoring resources, bilinguals outperform monolinguals. This observation suggests that bilingualism may affect the monitoring processes involved in executive control.     

An event-related brain potential analysis of visual word priming effects

Two experiments are reported that provide evidence on task-induced effects during visual lexical processing in a prime-target semantic priming paradigm. The research focuses on target expectancy effects by manipulating the proportion of semantically related and unrelated word pairs. In Experiment 1, a lexical decision task was used and reaction times (RTs) and event-related brain potentials (ERPs) were obtained. In Experiment 2, subjects silently read the stimuli, without any additional task demands, and ERPs were recorded. The RT and ERP results of Experiment 1 demonstrate that an expectancy mechanism contributed to the priming effect when a high proportion of related word pairs was presented. The ERP results of Experiment 2 show that in the absence of extraneous task requirements, an expectancy mechanism is not active. However, a standard ERP semantic priming effect was obtained in Experiment 2. The combined results show that priming effects due to relatedness proportion are induced by task demands and are not a standard aspect of online lexical processing.     

The role of category information in word identification: A parallel decision model

Four experiments consider the role of semantic category information in word identification using a serial classification reaction time paradigm. Experimental variables were manipulated by varying the semantic properties of blocks of trials and the target search instructions. Experiments 1, 2, and 3 investigated the facilitation on target word recognition of manipulating the categorical homogeneity of the nontarget words. An homogeneous nontarget set facilitated the classification of unrelated target words. This category contrast effect was obtained in all conditions, although its magnitude depended upon target search instructions. Experiment 3 also investigated whether word identification was inhibited if subjects were prevented from utilizing the category information to distinguish target from nontarget words. Target and nontarget word identification was slower under such conditions. Experiment 4 demonstratd that both the category contrast and category interference effects were dependent upon the use of short response-stimulus intervals to define a functional semantic background. This suggests the category effects are perceptual in nature. Current models of word recognition cannot easily explain the findings. A committee decision model is outlined to accommodate the data; the model proposes that visual analysis, identification, and categorization proceed in parallel.     

Effects of type of cognitive demand on bilateral advantage in interhemispheric processing

The relationship between cognitive task demand and effect of bilateral advantage (BLA) was examined. In Experiment 1, the task demand based upon visual stimulus complexity was manipulated. One-digit and two-digit numbers were presented in the left, right or both visual fields tachistoscopically and subjects were requested to identify the numbers. The results showed no BLA, although a right visual field advantage was demonstrated. In Experiment 2, cognitive demand in terms of memory was manipulated. Subjects were asked to recall one-digit numbers that were presented successively once, three and five times in the left, right or the both visual fields. The results did not show any sign of BLA in the recall of numbers. In Experiment 3, a greater memory load task was given than that in Experiment 2, where two-digit numbers were presented successively (once, three and five times). Subjects were asked to recall the numbers. The results showed a significant BLA in the recall of numbers, i.e., the correct numbers in the correct temporal positions. These results strongly suggest that a benefit of redundant bilateral visual fields presentation is shown only in a highly cognitively demanding task, especially when it involves phonological memory loads.     

The properties of object representations constructed during visual search in natural scenes

To investigate properties of object representations constructed during a visual search task, we manipulated the proportion of trials/task within a block: In a search-frequent block, 80% of trials were search tasks; remaining trials presented a memory task; in a memory-frequent block, this proportion was reversed. In the search task, participants searched for a toy car (Experiments 1 and 2) or a T-shape object (Experiment 3). In the memory task, participants had to memorize objects in a scene. Memory performance was worse in the search-frequent block than in the memory-frequent block in Experiments 1 and 3, but not in Experiment 2 (token change in Experiment 1; type change in Experiments 2 and 3). Experiment 4 demonstrated that lower performance in the search-frequent block was not due to eye-movement behaviour. Results suggest that object representations constructed during visual search are different from those constructed during memorization and they are modulated by type of target.     

Automatic activation of phonological information in reading: Evidence from the semantic relatedness decision task

A semantic relatedness decision task was used to investigate whether phonological recoding occurs automatically and whether it mediates lexical access in visual word recognition and reading. In this task, subjects read a pair of words and decided whether they were related or unrelated in meaning. In Experiment 1, unrelated word-homophone pairs (e.g., LION-BARE) and their visual controls (e.g., LION-BEAN) as well as related word pairs (e.g., FISH-NET) were presented. Homophone pairs were more likely to be judged as related or more slowly rejected as unrelated than their control pairs, suggesting phonological access of word meanings. In Experiment 2, word-pseudohomophone pairs (e.g., TABLE-CHARE) and their visual controls (e.g., TABLE-CHARK) as well as related and unrelated word pairs were presented. Pseudohomophone pairs were more likely to be judged as related or more slowly rejected as unrelated than their control pairs, again suggesting automatic phonological recoding in reading.