A hierarchical approach for fitting curves to response time measurements

Understanding how response time (RT) changes with manipulations has been critical in distinguishing among theories in cognition. It is well known that aggregating data distorts functional relationships (e.g., Estes, 1956). Less well appreciated is a second pitfall: Minimizing squared errors (i.e., OLS regression) also distorts estimated functional forms with RT data. We discuss three properties of RT that should be modeled for accurate analysis and, on the basis of these three properties, provide a hierarchical Weibull regression model for regressing RT onto covariates. Hierarchical regression model analysis of lexical decision task data reveals that RT decreases as a power function of word frequency with the scale of RT decreasing 11% for every doubling of word frequency. A detailed discussion of the model and analysis techniques are presented as archived materials and may be downloaded from www.psychonomic.org/archive.     

The overlap model: a model of letter position coding

Recent research has shown that letter identity and letter position are not integral perceptual dimensions (e.g., jugde primes judge in word-recognition experiments). Most comprehensive computational models of visual word recognition (e.g., the interactive activation model, J. L. McClelland & D. E. Rumelhart, 1981, and its successors) assume that the position of each letter within a word is perfectly encoded. Thus, these models are unable to explain the presence of effects of letter transposition (trial-trail), letter migration (beard-bread), repeated letters (moose-mouse), or subset/superset effects (faulty-faculty). The authors extend R. Ratcliff's (1981) theory of order relations for encoding of letter positions and show that the model can successfully deal with these effects. The basic assumption is that letters in the visual stimulus have distributions over positions so that the representation of one letter will extend into adjacent letter positions. To test the model, the authors conducted a series of forced-choice perceptual identification experiments. The overlap model produced very good fits to the empirical data, and even a simplified 2-parameter model was capable of producing fits for 104 observed data points with a correlation coefficient of .91.     

A practical method for analyzing factorial designs with heteroscedastic data

The Type I error rates and powers of three recent tests for analyzing nonorthogonal factorial designs under departures from the assumptions of homogeneity and normality were evaluated using Monte Carlo simulation. Specifically, this work compared the performance of the modified Brown-Forsythe procedure, the generalization of Box's method proposed by Brunner, Dette, and Munk, and the mixed-model procedure adjusted by the Kenward-Roger solution available in the SAS statistical package. With regard to robustness, the three approaches adequately controlled Type I error when the data were generated from symmetric distributions; however, this study's results indicate that, when the data were extracted from asymmetric distributions, the modified Brown-Forsythe approach controlled the Type I error slightly better than the other procedures. With regard to sensitivity, the higher power rates were obtained when the analyses were done with the MIXED procedure of the SAS program. Furthermore, results also identified that, when the data were generated from symmetric distributions, little power was sacrificed by using the generalization of Box's method in place of the modified Brown-Forsythe procedure.     

When credibility attacks: The reverse impact of source credibility on persuasion

Recent research on the self-validation hypothesis suggests that source credibility identified after message processing can influence the confidence people have in their own thoughts generated in response to persuasive messages (Briñol, Petty, & Tormala, 2004). The present research explored the implications of this effect for the possibility that high credibility sources can be associated with more or less persuasion than low credibility sources. In two experiments, it is demonstrated that when people generate primarily positive thoughts in response to a message (e.g., because the message contains strong arguments) and then learn of the source, high source credibility leads to more favorable attitudes than does low source credibility. When people have primarily negative thoughts in response to a message (e.g., because it contains weak arguments), however, this effect is reversed—that is, high source credibility leads to less favorable attitudes than does low source credibility.     

A challenging dissociation in masked identity priming with the lexical decision task

The masked priming technique has been used extensively to explore the early stages of visual-word recognition. One key phenomenon in masked priming lexical decision is that identity priming is robust for words, whereas it is small/unreliable for nonwords. This dissociation has usually been explained on the basis that masked priming effects are lexical in nature, and hence there should not be an identity prime facilitation for nonwords. We present two experiments whose results are at odds with the assumption made by models that postulate that identity priming is purely lexical, and also challenge the assumption that word and nonword responses are based on the same information. Our experiments revealed that for nonwords, but not for words, matched-case identity PRIME–TARGET pairs were responded to faster than mismatched-case identity prime–TARGET pairs, and this phenomenon was not modulated by the lowercase/uppercase feature similarity of the stimuli.     

Reconsolidation of declarative memory in humans

The reconsolidation hypothesis states that a consolidated memory could again become unstable and susceptible to facilitation or impairment for a discrete period of time after a reminder presentation. The phenomenon has been demonstrated in very diverse species and types of memory, including the human procedural memory of a motor skill task but not the human declarative one. Here we provide evidence for both consolidation and reconsolidation in a paired-associate learning (i.e., learning an association between a cue syllable and the respective response syllable). Subjects were given two training sessions with a 24-h interval on distinct verbal material, and afterward, they received at testing two successive retrievals corresponding to the first and second learning, respectively. Two main results are noted. First, the first acquired memory was impaired when a reminder was presented 5 min before the second training (reconsolidation), and also when the second training was given 5 min instead of 24 h after the first one (consolidation). Second, the first retrieval proved to influence negatively on the later one (the retrieval-induced forgetting [RIF] effect), and we used the absence of this RIF effect as a very indicator of the target memory impairment. We consider the demonstration of reconsolidation in human declarative memory as backing the universality of this phenomenon and having potential clinical relevance. On the other hand, we discuss the possibility of using the human declarative memory as a model to address several key topics of the reconsolidation hypothesis.     

When head is tempered by heart: Heart rate variability modulates perception of other-blame reducing anger

This study examined the relationship between heart rate variability (HRV), as an index of individual differences in emotion regulation, and perception of other-blame, as a mechanism of anger induction. The physiological responses were recorded while subjects read a story from a computer screen. The story narrated a negative event in self-referred way -dismissal from a job as the result of a colleague’s action- under conditions of intentionality versus non-intentionality. Cognitive and emotional variables were assessed by questionnaire immediately after the physiological test. The resulting structural model supports the conclusion that HRV exerts its regulatory influence directly on perception of other-blame rather than on emotion. In situations of intentionality, individuals with higher HRV make less extreme evaluation of the offender’s blame, versus those with lower HRV, thus leading to a reduction in anger reaction. These results suggest that HRV is a direct index of cognitive rather than emotional regulation.     

Bobwhite quail (Colinus virginianus) hatchlings track the direction of human gaze

Gaze following allows individuals to detect the locus of attention of both conspecifics and other species. However, little is known about how this ability develops. We explored the emergence of bobwhite quail hatchlings’ ability to track human gaze by assessing their avoidance behavior in an open arena under five testing conditions: (1) a Direct Gaze condition, in which an experimenter looking down was positioned above one of two approach areas; (2) a Gaze Follow condition in which an experimenter, positioned equidistant between two approach areas, directed his/her gaze towards one of the areas; (3) a Masked Gaze Follow condition, in which the experimenter wore a mask during the Gaze Follow test; (4) a Deprived Face Experience condition, in which hatchlings were deprived of experience with human faces prior to the Gaze Follow test; and (5) a Control condition in which no experimenter was present during testing. Results revealed that hatchlings from the Direct Gaze condition preferred the non-gazed approach area at all ages tested. Hatchlings from the Gaze Follow condition preferred the non-gazed approach area at 48 and 72 h, but not at 24 h of age. In contrast, hatchlings from the Masked Gaze Follow, Deprived Face and Control conditions did not prefer either approach area at any age tested. These results indicate that experience with human faces plays a key role in the rapid emergence of gaze following behavior in bobwhite quail hatchlings.     

A model of the go/no-go task

In this article, the first explicit, theory-based comparison of 2-choice and go/no-go variants of 3 experimental tasks is presented. Prior research has questioned whether the underlying core-information processing is different for the 2 variants of a task or whether they differ mostly in response demands. The authors examined 4 different diffusion models for the go/no-go variant of each task along with a standard diffusion model for the 2-choice variant (R. Ratcliff, 1978). The 2-choice and the go/no-go models were fit to data from 4 lexical decision experiments, 1 numerosity discrimination experiment, and 1 recognition memory experiment, each with 2-choice and go/no-go variants. The models that assumed an implicit decision criterion for no-go responses produced better fits than models that did not. The best model was one in which only response criteria and the nondecisional components of processing changed between the 2 variants, supporting the view that the core information on which decisions are based is not different between them.