Multiple spatial codes and temporal overlap in choice-reaction tasks

Experiments by Umiltà and Liotti (1987) and Lamberts, Tavernier, & d'Ydewalle (1992) examined the Simon effect (an influence of irrelevant stimulus location on reaction time) as a function of multiple frames of reference. The Simon effect was absent for all reference frames in the former experiment, leading Stoffer (1991) to propose that a spatial code is formed only if the last step in directing attention to the imperative stimulus is a lateral shift. However, the Simon effect was evident for all frames in the latter experiment. Hommel (1994) proposed that the multiple spatial codes implied by Lamberts et al.'s findings were also activated in Umiltà and Liotti's experiment but had decayed by the time the relevant stimulus information had been identified. Experiments 1, 2, and 3 examined these accounts of attention shifting, multiple codes, and temporal overlap for variations of the Simon task in which the stimulus could occur in one of either eight or four possible stimulus locations. Three stimulus sets that differed in ease of discriminability were used in each experiment. Experiments 1 and 2 were replications and extensions of those of Lamberts et al. and Umiltá and Liotti, respectively. In both experiments, two boxes, with a stimulus inside of one, appeared simultaneously, and the subject was to respond to the identity of the stimulus. Experiment 3 used a procedure in which the four stimulus locations were demarcated by three vertical lines. Two of the three experiments showed Simon effects with respect to multiple frames of reference, and the magnitude of these effects was a decreasing function of the difficulty of stimulus discriminability. Spatial compatibility proper was examined in Experiment 4 using the same layout as Experiment 3. In this case, only the relevant frame of reference was coded. On the whole, the results indicate that multiple codes are formed, but not automatically, and that those codes decay when irrelevant.     

Electrocortical Responses to ecologically relevant visual stimuli among professional drivers with and without cardiovascular disease

Electrocortical responses were assessed using two simulated aspects of visual signals encountered in traffic: the Glare Pressor Test (GPT) and Event-Related Potential Avoidance Task (ERPAT) among four groups of male professional drivers: 12 with ischemic heart disease (IHD), 12 hypertensives, 10 borderline hypertensives, 34 who were apparently healthy and 23 nonprofessional driver healthy control subjects. The blood pressure (BP) responses immediately after the ERPAT were also measured. There was a significant between groups effect for the amplitude of the target N2 component in the ERPAT (p=0.02), with the lowest means among the drivers with IHD and the highest among those with hypertension. Drivers with IHD also showed the highest diastolic BP reactivity to the ERPAT. Significantly more than the expected number of drivers with IHD failed to recover alpha activity after the first glare impulse of the GPT. Professional drivers who failed to recover baseline levels of alpha activity after the GPT showed a significantly smaller N2 amplitude compared to those who recovered (p=0.01). There was a positive correlation between abundance of alpha activity at rest with P300 amplitude (p=0.02). An inverse relation was found between number of work hours behind the wheel and the amplitude of the target P300 (p=0.04). Results are interpreted in light of recent advances concerning integrative mechanisms of defence versus vigilance response patterns. The findings in this study justify further applications of these psychophysiologic methods to assess the relationship between simulated signals of the work environment and mechanisms of cardiac risk in this occupational group.     

Cross-task cross talk in memory and perception

The application of the additive factors method depends on finding factors that selectively influence processing stages. When all the processes for a task are in series, a factor directly influencing a process might change its output and thereby have indirect influence on succeeding processes. We investigate whether such indirect influence is possible between processes associated with different tasks being performed together. In two dual-task memory scanning and arithmetic experiments with digits as the stimuli for both tasks, information relevant for only one of the tasks nonetheless affected performance of the other. When the same digit was relevant for the two tasks, cross-task facilitation and interference were observed in some cases. Displaying the same digit for both tasks led to relatively fast response times, paralleling the effect of flankers in the response competition paradigm. But repetition of digits in memory slowed responses. It is suggested that the need for control processes to keep task information segregated is responsible for the pattern of effects.     

A probabilistic formulation and statistical analysis of guttman scaling

By proposing that the latent or true nature of subjects is identified with a limited number of response patterns (the Guttman scale patterns), the probability of an observed response pattern can be written as the sum of products of the probability of the true type multiplied by the chance of sufficient response error to cause the observed pattern to appear. This model contains the proportions of the true types as parameters plus some misclassification probabilities as parameters. Maximum likelihood methods are used to make estimates and test the fit for some examples.     

Reorganization of Equivalence Classes After Reversal of Baseline Relations

The Psychological Record - Pilgrim and Galizio (1995) reversed baseline conditional discriminations after the emergence of equivalence classes. College students’ performance was consistent...     

Effects of face and inanimate-object contexts on stimulus–response compatibility

Prior studies have shown that a left–right spatial compatibility effect occurs for vertically oriented stimuli relative to a background context of a face rotated 90° clockwise or counterclockwise from upright. For stimuli presented at the location of the eyes, the mapping of the right eye to a right response and the left eye to a left response, as would be viewed by the participant, yields better performance than does the opposite mapping. An issue of current interest in social cognition is whether animate objects are processed differently from inanimate ones. We investigated this issue in two experiments in which we compared the compatibility effects obtained with inanimate objects to those obtained with animate, face stimuli. The results showed left–right compatibility effects from the participant’s perspective for vehicles and faces from frontal and profile views, as well as for a road sign. Our findings indicate that coding of stimulus location relative to an external frame of reference is not restricted to face backgrounds.     

Making Reading More Difficult: A Degraded Text Microworld for Teaching Reading Comprehension Strategies

We present an empirical study that investigated seventh-, ninth-, and eleventh-grade students’ understanding of the infinity of numbers in an interval. The participants (n = 549) were asked how many (i.e., a finite or infinite number of numbers) and what type of numbers (i.e., decimals, fractions, or any type) lie between two rational numbers. The results showed that the idea of discreteness (i.e., that fractions and decimals had “successors” like natural numbers) was robust in all age groups; that students tended to believe that the intermediate numbers must be of the same type as the interval endpoints (i.e., only decimals between decimals and fractions between fractions); and that the type of interval endpoints (natural numbers, decimals, or fractions) influenced students’ judgments of the number of intermediate numbers in those intervals. We interpret these findings within the framework theory approach to conceptual change.     

The Simon Effect With Wheel-Rotation Responses

The authors examined clockwise and counterclockwise wheel-rotation responses to high- or low-pitched tones presented in participants' (N = 96, Experiment 1; N = 48, Experiment 2; N = 48, Experiment 3) left and right ears. In Experiment 1, a Simon effect (fastest responding when tone location and direction of wheel turn corresponded) was obtained when participants' hands were at the top or middle of the wheel but not at the bottom. With line bottom hand placement, a Simon effect was induced by instructions emphasizing hand movements but not by instructions emphasizing wheel movements (Experiment 2), and by a visual cursor controlled by the wheel but not one triggered by the response (Experiment 3). The results of the experiments showed that the nature of the task and the instructed action goal influence the direction of the Simon effect.     

Shared spatial representations for physical locations and location words in bilinguals’ primary language

For monolinguals, the Simon effect is eliminated when Simon task trials are intermixed with ones in which participants respond to the words left and right with incompatibly mapped keypresses. For bilingual Dutch/ French speakers, this result has been shown to occur when the words are in Dutch (their first and primary language), but not when they are in French. To dissociate the influence of order in which the languages were learned from whether the language was the primary one currently being used, we tested bilinguals who learned Spanish or Vietnamese as their first language but for whom English became their primary language. For both groups, the incompatible location-word mapping influenced performance of the Simon task when the words were in English but not when they were in the first language. These findings indicate that the strength of language, not order of acquisition, is the critical factor.