Combined expectancy effects: an accumulator model

When participants use cues to prepare for a likely stimulus or a likely response, reaction times are facilitated by valid cues but prolonged by invalid cues. In studies on combined expectancy effects, two cues give information regarding two dimensions of the forthcoming task. When the two cues consist of two separable stimuli their effects are approximately additive. When cues are presented as an integrated stimulus, cueing effects interact. A model is presented that simulates effects like these. The model assumes that cues affect different processing stages. When implicit information suggests that expectancies are unrelated, as for instance with separated cues, cueing effects at early and late levels of processing remain independent. When implicit information suggests that expectancies are related, as with integrated cues, however, a mechanism that is sensitive to the validity of the early stage cue, leads to an adjustment of the cueing effect at the late stage. The model is based on neurophysiologically plausible assumptions, it is given explicitly in mathematical terms, and it provides a good fit to a large body of empirical data.     

Acts of perceptual inquiry: problems for any stimulus-based simplicity theory

Stimulus-specified simplicity is simply insufficient to predict the appearance of objects' 3D forms and figural shapes, etc., as originally intended. Which information a viewer chooses to attend can determine both what 3D structure is perceived and its attendant perceptual consequences; moreover, a shape's meaningfulness or denotivity [M.A. Peterson, Current Directions in Psychological Science 3 (1994) 105] can overcome simplicity-based figure-ground segregation. In both cases, perceptual consequences, such as subsequent perceived movements, are constrained or primed in ways that can help us corroborate and define what the viewer has perceived; that may help us in studying the underlying events in brain processing; and that should help in designing such perceptual applications as still and animated displays. Demonstrations, theoretical framework, and potential research tools are offered.     

Influence of prime-target relationship on semantic priming effects from words in a lexical-decision task

The present research examines the influence of prime-target relationship (associative and categorical versus categorical only) on priming effects from attended and ignored parafoveal words. Participants performed a lexical-decision task on a single central target, which was preceded by two parafoveal prime words, one of which (the attended prime) was spatially precued. The results showed reliable positive and negative priming effects from attended and ignored words, respectively. However, this priming pattern was observed only for the "associative and categorical", but not for the "categorical only" relationship condition. These results suggest that the lack of semantic priming effects from words in some prior studies may be attributed to the kind of material used (i.e. weakly-associated word pairs).     

Age differences in response selection for pure and mixed stimulus-response mappings and tasks

Two experiments examined effects of mixed stimulus-response mappings and tasks for older and younger adults. In Experiment 1, participants performed two-choice spatial reaction tasks with blocks of pure and mixed compatible and incompatible mappings. In Experiment 2, a compatible or incompatible mapping was mixed with a Simon task for which the mapping of stimulus color to location was relevant and stimulus location was irrelevant. In both experiments, older adults showed larger mixing costs than younger adults and larger compatibility effects, with the differences particularly pronounced in Experiment 1 when location mappings were mixed. In mixed conditions, when stimulus location was relevant, older adults benefited more than younger adults from complete repetition of the task and stimulus from the preceding trial. When stimulus location was irrelevant, the benefit of complete repetition did not differ reliably between age groups. The results suggest that the age-related deficit associated with mixing mappings and tasks is primarily due to older adults having more difficulty separating task sets that activate conflicting response codes.     

Modulating the attentional repulsion effect

The attentional repulsion effect refers to the perceived displacement of a visual stimulus in a direction that is opposite to a brief peripheral cue. If the spatial repulsion brought about by peripheral cues is in fact attentional in nature, then attentional manipulations that produce known effects on reaction time should have analogous spatial repulsions effects. Across three experiments, we show that the attentional repulsion effect does indeed mimic results obtained from temporal (i.e., reaction time) attentional tasks, including single onset, offset and onset-offset cue displays (Experiment 1), simultaneous onset and offset displays (Experiment 2), and pop-out color displays (Experiment 3). Thus, the attentional repulsion effect can be modulated by attentional manipulations. Moreover, it appears that attentional processes underlying changes related to when targets are perceived appear to be the same as those underlying changes related to perceiving where targets are.     

Effect of time of day on arithmetic fact retrieval in a number-matching task

The goal of this study is aimed to investigate a possible effect of time of day on arithmetic fact retrieval in a number-matching task. We tested 96 students (age range 19-33 years) at 9 a.m. and at 1 p.m., in a counterbalanced order. The subjective alertness levels were also recorded. As regards retrieval efficiency, the results showed that the sum interference effect was significantly more pronounced in the morning (9 a.m.) than at midday (1 p.m.). As expected, participants showed higher subjective alertness levels at 1 p.m. than at 9 a.m.. However, the difference of subjective alertness did not completely explain differences in interference at two testing sessions. The results could be explained with respect to the variation of working memory efficiency during the day.     

Sequential effects within a short foreperiod context: evidence for the conditioning account of temporal preparation

Responses to an imperative stimulus (IS) are especially fast when they are preceded by a warning signal (WS). When the interval between WS and IS (the foreperiod, FP) is variable, reaction time (RT) is not only influenced by the current FP but also by the FP of the preceding trial. These sequential effects have recently been proposed to originate from a trace conditioning process, in which the individuals learn the temporal WS-IS relationship in a trial-by-trial manner. Research has shown that trace conditioning is maximal when the temporal interval between the conditioned and unconditioned stimulus is between 0.25 and 0.60 s. Consequently, one would predict that sequential effects occur especially within short FP contexts. However, this prediction is contradicted by Karlin [Karlin, L. (1959). Reaction time as a function of foreperiod duration and variability. Journal of Experimental Psychology, 58, 185-191] who did not observe the typical sequential effects with short FPs. To investigate temporal preparation for short FPs, three experiments were conducted, examining the sequential FP effect comparably for short and long FP-sets (Experiment 1), assessing the influence of catch trials (Experiment 2) and the case of a very dense FP-range (Experiment 3) on sequential FP effects. The results provide strong evidence for sequential effects within a short FP context and thus support the trace conditioning account of temporal preparation.     

The effects of video game playing on attention, memory, and executive control

Expert video game players often outperform non-players on measures of basic attention and performance. Such differences might result from exposure to video games or they might reflect other group differences between those people who do or do not play video games. Recent research has suggested a causal relationship between playing action video games and improvements in a variety of visual and attentional skills (e.g., [Green, C. S., & Bavelier, D. (2003). Action video game modifies visual selective attention. Nature, 423, 534-537]). The current research sought to replicate and extend these results by examining both expert/non-gamer differences and the effects of video game playing on tasks tapping a wider range of cognitive abilities, including attention, memory, and executive control. Non-gamers played 20+ h of an action video game, a puzzle game, or a real-time strategy game. Expert gamers and non-gamers differed on a number of basic cognitive skills: experts could track objects moving at greater speeds, better detected changes to objects stored in visual short-term memory, switched more quickly from one task to another, and mentally rotated objects more efficiently. Strikingly, extensive video game practice did not substantially enhance performance for non-gamers on most cognitive tasks, although they did improve somewhat in mental rotation performance. Our results suggest that at least some differences between video game experts and non-gamers in basic cognitive performance result either from far more extensive video game experience or from pre-existing group differences in abilities that result in a self-selection effect.     

Developmental changes in oculomotor control and working-memory efficiency

In the present study, we examined the developmental changes in the efficiency of saccadic inhibitory control. More specifically, the contribution of age-related changes in working-memory engagement was investigated. We manipulated the efficiency of inhibitory oculomotor control in antisaccade tasks by using fixation-offset conditions, which are supposed to affect inhibitory demands, and by adding increasing working-memory loads to the antisaccade task. In general, in comparison to antisaccade performance of adults, the antisaccade performance of 8-year-old and 12-year-old children was characterized by an increase in direction errors, and/or longer saccadic onset latencies on correct antisaccades. However, this pattern was not altered by the fixation-offset manipulations. In contrast, increased working-memory demands deteriorated 8-year-olds' antisaccade performance unequally as compared to older children and young adults. These findings suggest that - at least in young children - the available functional working-memory capacity is engaged in oculomotor inhibition.     

Is there a general task switching ability?

Participants were tested on two analogous task switching paradigms involving Shape/Size tasks and Vertical/Horizontal tasks, respectively, and three measures of psychometric intelligence, tapping fluid, crystallized and perceptual speed abilities. The paradigms produced similar patterns of group mean reaction times (RTs) and the vast majority of the participants showed switching cost (switch RT minus repeat RT), mixing cost (repeat RT minus single-task RT) and congruency effects. The shared intra-individual variance across paradigms and with psychometric intelligence served as criteria for general ability. Structural equations modeling indicated that switching cost with ample preparation ("residual cost") and mixing cost met these criteria. However, switching cost with little preparation and congruency effects were predominantly paradigm specific.