Creativity involved every aspect of social life. Numerous brain imaging researchers had explored the activation in the brain using a myriad of creative tasks, such as divergent thinking tasks, verbal and figural creative tasks, mental imagery, the generation of creative stories and paintings. Scientific innovation was one of the most important forms of creative thinking. The cases of creation and innovation happened in the real world had been used to study the mechanism behind creativity. However, the functions of implicated brain regions remained poorly understood. The present study employed resting-state functional magnetic resonance imaging (rs-fMRI) to investigate the neural substrates for the process of the scientific innovation problem solving.
In the present study, 65 scientific innovation problems were selected from the real world and divided into novel scientific innovation (NSI) problems and old scientific innovation (OSI) problems (36 NSI problems and 29 OSI problems). Each problem consisted of two parts: heuristic prototype and the corresponding question. Numerous studies showed that the heuristic prototype inspired the solution of insightful problems. The modified “learning-test two-phase” paradigm was used. Specifically, we asked the subjects to learn all the heuristic prototypes one day before the experiment, and then resolve the corresponding problems randomly in the test phase of the experiment. 16 undergraduates (mean age = 21.19 ± 1.76) were enrolled in the experiment. The rs-fMRI data was acquired using Echo Planar Imaging (EPI) sequence from a 3-T Siemens Magnetom Trio scanner (Siemens Medical, Erlangen, Germany) with a 12-channel phased-array head coil housed at MRI center of Southwest University. This scanning acquired 242 volumes in 8 min and 8 sec. Brain imaging data was processed and analyzed using the REST (Resting-State fMRI Data Analysis Toolkit) toolbox to calculate ReHo (Regional Homogeneity) and ALFF (Amplitude of Low Frequency Fluctuation). We used both ReHo and ALFF to measure the local properties of rs-fMRI signals, and then investigated the relationship between ReHo/ALFF and individual differences in creativity, as measured by the NSI problem solving. The multiple comparisons correction was calculated using the AlphaSim program in REST software.
After controlling for the age, gender and the accuracy rate of OSI problem solving, the results of multiple regression analysis showed that the ReHo of the anterior cingulate cortex (ACC) was positively correlated with creativity as measured by the accuracy rate of NSI problem solving. The results of the analysis of ALFF were consistent with that of ReHo.
The result of both ReHo and ALFF implied that the ACC was played an important role in the process of scientific innovation problem solving. We discussed the role of the ACC from two aspects: one involved in breaking the thinking set and forming the novel association, another involved in the demand of information processing.
It has been estimated that more than half of the world’s population is bilingual. In the past few decades, numerous studies have shown that bilinguals have an advantage in selecting relevant information, inhibiting competing and distracting information than monolinguals (e.g., Bialystok, Craik, Klein, & Viswanathan, 2004; Costa, Hernández, & Sebastián-Gallés., 2008, to name just a few). Recent research has instead shown a more nuanced story: bilinguals and monolinguals perform equally in either the Stroop or flanker task (Paap & Greenberg, 2013; Sawi & Paap, 2013). To date, it is still hard to confirm that bilinguals have an advantage in language inhibition. While the vast majority of bilingual research has exclusively focused on the study of spoken language users – ‘unimodal’ bilinguals, bimodal bilinguals have received scant attention. ‘Bimodal’ bilinguals, who have acquired a spoken and a signed language, can provide a unique testbed for the bilingual advantage effect. In addition, few studies have looked at whether different second language proficiencies contribute to the same language inhibitory ability in unimodal and bimodal bilinguals. Therefore, the current study examined language inhibition ability in unimodal (English-Chinese) and bimodal (English-American Sign Language) bilinguals with both low and high L2 proficiency.
In Experiment 1 and 2, a homograph interference task was used to investigate bilingual advantage in conflict resolution during sentence processing. Participants were asked to read a sentence ending with a homograph (e.g., He walked along the bank.) and then judge if a target word (e.g., RIVER or MONEY) matched the meaning of the sentence they just read. Although the target word (e.g., MONEY) is semantically related to one meaning of the homograph (bank: a financial institution), it is not the meaning supported by the sentence context (e.g., He walked along) and, consequently, this alternative meaning must be suppressed in order to correctly respond “no”. Thus, a measure of homograph interference can be computed by comparing the mean RT for the target words semantically relevant to the sentences or not.
Experiment 1 showed that the unimodal bilinguals with higher L2 (Chinese) proficiency outperformed the unimodal bilinguals with lower L2 proficiency and the monolinguals on the homograph interference task that required resolving conflict from competing alternative meanings. In addition, there was no difference between the unimodal bilinguals with lower L2 proficiency and the monolinguals. In Experiment 2, there was no performance difference in the homograph interference task between the bimodal bilinguals with higher L2 (American Sign Language) proficiency, the bimodal bilinguals with lower L2 proficiency and the monolinguals. Taken together, the results across the two experiments indicate that both L2 modality and L2 proficiency are mediating factors of bilingual advantage effect.
According to the results of the two experiments, one possible explanation for this enhancement of language inhibitory ability in unimodal bilinguals is that the regular use of two languages requires a mechanism to select the target language and inhibit the non-target language—an experience that may enhance general control mechanism. By contrast, bimodal bilinguals can always sign (gesture) and speak at the same time. The comprehension and production of their two languages involve distinct sensory-motor and perceptual systems, leading to weaker demand on language inhibition. Together, these results attribute the bilingual advantage in linguistic inhibition ability to the unimodal bilingual’s experience of controlling two languages in the same modality.
The negative cognitive bias is common in affective disorder patients, which is resistance to treatment and recovery. Cognitive reappraisal is an emotion regulation strategy that involves the process of changing the emotion response by reinterpreting the meaning of the emotional stimulus. It has been shown that cognitive reappraisal decreases negative cognitive and emotion valance effectively. Conditioned fear is an important model of affective disorder. However, whether reappraisal changes the negative cognitive and emotion in the conditioned fear is controversial. Here, we investigate whether the short-term cognitive reappraisal training could change the process of conditioned fear for individuals with low reappraisal ability and further reveal the influence of cognitive reappraisal on the acquisition and extinction of conditioned fear.
Sixty-eight healthy individuals whose reappraisal scores were below the median of emotion regulation queationnaire were recruited and then assigned to reappraisal group and control group randomly. One or two days before the fearing condition, the experiment group was trained to reappraisal and learn how to decrease negative emotion to negative or neutral pictures. Like the program of Shurick (2013), the reappraisal training consisted of three parts: First, Participants were asked to talk about their feelings on a neutral picture such as “a person lying on a hospital bed”. Second, they were asked to reappraise the picture to reduce the negative emotion and isolate the emotional association between different pictures, such as, “although the person seems weak, it is merely a scene in a film and is not real”. To isolate the emotional association between two pictures, for example, one picture was a dog and the other picture was a patient. The negative association was that “the dog bitted the person seriously and the person was treated in hospital”, while the positive association would decrease negative emotion. for example, “the dog was waiting for its master who was in the hospital”. Third, the participants were asked to practice reappraisal to life events and negative pictures. The differential conditioned fear paradigm was used in two days. Participants were asked to complete acquisition and extinction of conditioned fear on the first day and re- extinction on the second day (24 hours later). CS fear valance were orally reported during the time of pre-acquisition, post-acquisition, post-extinction, pre re-extinction and post re-extinction. All pictures were displayed and the US expectancy was recorded by the e-prime 1.1 during the conditions of acquisition, extinction and re-extinction. CS fear, and US-expectancy were analyzed using a mixed analysis of variance (ANOVA) for repeated measures with the groups as the between-subjects factor, and stimulus (CS− vs. CS+) and trial (i.e., stimulus presentation) as the within-subjects factors.
A time × group repeated measures ANOVA indicated that CS fear increased significantly from pre-acquisition to post-acquisition [F(1, 61) = 44.56, p < 0.001, η2 = 0.76] and decreased remarkably from post-acquisition to post-extinction [F(1, 61) = 13.56, p < 0.05, η2 = 0.53] in two groups. The independent samples t-test for CS fear showed that, a significant difference in CS+ was observed between the reappraisal and control groups [post-acquisition: CS+ (t(28) = 10.32, p < 0.01), CS− (t(28) = 4.32, p = 0.0502); post-extinction: (CS+: t(28) = 11.58, p < 0.05; CS−: t(28) = 1.43, p = 0.282); pre re-extinction (CS+:t(28) = 25.63, p < 0.001;CS−: t(28) = 12.72, p < 0.05)]. A trial × CS type × group repeated measures ANOVA of US expectancy revealed that both groups acquired fear at acquisition [F(1,61) = 4.34, p = 0.069] and showed no differences. However, the interaction of group × type was significant [F(1,61) = 5.54, p = 0.047] at extinction, great difference were revealed by one samples t-test for CS+ and CS− [ CS+: t(28) = 7.11, p < 0.01 and CS−: t(28) = 10.40, p < 0.001]. The US expectancy of CS+ was much lower and declined faster in reappraisal group than that in the control group, F(1,61) = 72.26, p < 0.001, η2 = 0.53. In the last trial at extinction, the US expectancy to CS was still observed significant differences between groups (CS+: t(28) = 19.26, p < 0.001; CS−: t(28) = 11.06, p < 0.05). At re-extinction on the second day, the US expectancy of trials showed that both groups extinct the conditioned fear successfully, F(11,647) = 27.26, p < 0.001, η2 = 0.52. Compared to the US expectancy of e12 (the last trail of first extinction) and E1 (the first trail of re-extinction), the CS expectancy of the reappraisal group were much lower than those of the control group (CS−: t(28) = 12.12, p < 0.05; CS+: t(28) = 18.42, p < 0.001), which indicated that reappraisal promotes the extinction of conditioned fear and inhibited the return of conditioned fear.
In conclusion, the short-term reappraisal training can reduce the negative emotion effectively for the individuals with low scores of cognitive reappraisal, without changing the ability to distinguish safe signals from dangerous signals in the acute stress state. Moreover, cognitive reappraisal effectively reduces the fear in acquisition and extinction of conditioned fear and improve the conditioned fear extinction, as well as inhibited the return of conditioned fear.
Time perception/judgment is relevant to everyone and is an integral part of decision making, because any meaningful choices are embedded in a temporal context. The unpacking effect (Tversky & Koehler, 1994) in probability judgment refers to a phenomenon where “unpacking” an event could increase the subjective probability judgment of the event. Given the similarity of time and probability in intertemporal and risky decision making and based on the results of plan fallacy research, we conject that the unpacking effect may also be detected in time perception/judgment. Unlike previous research that focused on the unpacking manipulation of some events, we only used pure manipulation on a time interval. We named this phenomenon the time unpacking effect, where a time interval is presented in an unpacked rather than compact way, thus lengthening subjective time perception. In this research, two studies explored the time unpacking effect in judgment and intertemporal decision making, and the impact the effect has on intertemporal decision making.
Study 1 tested this effect in temporal judgment of whether a given time is sufficient to complete a task. Hypothesis 1a states that people in the unpacking condition compared with those in the packed condition will have higher scores, meaning they will perceive the time period as longer. Based on previous research, we formulated hypothesis 1b stating that task difficulty will affect the time unpacking effect. The experiment used a between-subjects design, where 124 participants were randomly assigned to a packed or unpacked condition and were presented with two scenarios within which tasks of varying difficulty were presented and asked to finish the corresponding computerized questionnaires. As a control factor we measured the participants’ degree of busyness during the specified time periods. A mixed design MANOVA revealed that the interaction of condition-by-difficulty degree was significant, F(1, 120) = 5.14, p < 0.05. Furthermore, in the second scenario, which had a lower degree of difficulty, the unpacking manipulation significantly influenced the participants’ time judgment (t(122) = −2.70, p < 0.01), while in the first scenario, the effect was not significant (t(122) = −0.77, p > 0.05). These results supported hypotheses 1a and 1b.
Study 2 tested the time unpacking effect and explored its influence on intertemporal decision making. Hypothesis 2a states that participants in the unpacking condition perceive time delay as longer in the larger but later (LL) option of intertemporal choice, and thus prefer the smaller but sooner (SS) option compared with participants in the packed condition. Hypothesis 2b states that time perception of delay in the LL option mediates the effect of unpacking manipulation on intertemporal choice. The design and procedure were the same as in study 1. A total of 124 participants finished one of two versions of the intertemporal choice computerized questionnaire containing two scenarios. MANOVA analysis found that in both scenarios, people in the unpacking condition perceived a longer time delay (first scenario: F1(1, 98) = 9.03, p1 < 0.01; second scenario: F2(1, 98) = 6.54, p2 < 0.05). They also preferred the SS option in intertemporal decision making, F1(1, 98) = 13.82, p1 < 0.001 and F2(1, 98) = 4.47, p2 < 0.05 in the first and second scenarios, respectively. These results supported hypothesis 2a. Meanwhile, bootstrap mediating analysis supported hypothesis 2b indicating that time perception of delay mediated the influence of unpacking manipulation on intertemporal choice at 90% confidence interval in the first scenario (−0.4660, −0.0220) and 95% confidence interval in the second scenario (−0.4621, −0.0151).
This research identified a new influencing factor in judgment and decision making called the time unpacking effect, and implemented two studies to demonstrate its robustness. Using either an indirect (study 1) or direct (study 2) way to measure time perception substantiated this effect. Our time unpacking effect could be explained by support theory, specifically the attentional explanation. Compared with other influencing factors of time perception, the time unpacking effect is easier to manipulate, therefore it has more practical value in our daily lives.
Advice taking, which is a decision-making process formulated by decision-makers with the reference of others’ suggestions, was investigated extensively in the field of behavioral decision making. To date, majority of researchers have studied the facilitating or hindering of the exchange of advice by situational factors, leaving plenty of variables relatively unexplored. A small numbers of studies that have included individual differences, such as intelligence, conscientiousness, emotion, power, etc., have found promising results. Self-esteem as an important variable in social psychology, affects the individual's social adaptation and mental health, but its influence on advice taking is still unexplored. Due to explicit self-esteem and implicit self-esteem are two independent dimensions, so we aim to explore the joint influence of explicit self-esteem and implicit self-esteem on advice taking.
Three experiments are designed to test our hypotheses. In study1, we investigated how explicit self-esteem, implicit self-esteem, and the discrepancies of explicit self-esteem and implicit self-esteem affect the advice taking process. In study 2, by priming the high implicit self-esteem, we intended to furtherly verify the influence of self-esteem discrepancies on advice taking. In study 3, we explored whether self-concept clarity mediated the relationship between self-esteem discrepancies and advice taking, thus to deepen the understanding for the mechanism of the discrepancies of self-esteem and advice taking.
310 university students participated in the three experiments, 106 in study 1, 74 in study 2, and 130 in study 3. Results showed that, the explicit self-esteem had a negative correlation with advice taking, and the influence of implicit self-esteem on advice taking was not significant, but the discrepancies of explicit self-esteem and implicit self-esteem affected advice taking. The self-concept clarity mediated the influence of self-esteem discrepancies on advice taking. Implications, limitations and future directions were discussed as well.
Even though there were several studies explored the relationship between LMX and employee helping behavior, there were three theoretical gaps in the extant research. Based on social exchange theory, this study proposed a homologous multilevel model to explore how multilevel LMX influenced employee and team helping behavior through the interpersonal justice and interpersonal justice climate.
Data was collected from 274 supervisor–subordinate dyads in 56 teams. Confirmatory Factor Analysis (CFA) was conducted to examine the distinctiveness of the three variables. The Hierarchical Linear Models (HLM) was applied to examine the mediation at individual and cross level while the multiple linear regression was used to examine the mediation and moderation at group level. Sobel test was employed to calculate the indirect effect of mediations.
The results revealed that: (1) LMX was positively related to employee helping behavior; (2) LMX Mean was positively related to employee and team helping behavior; (3) interpersonal justice fully mediated the impact LMX and LMX Mean on employee helping behavior; (4) interpersonal justice climate fully mediated the influence LMX Mean on individual and team helping behavior; (5) LMXD negatively moderated the relationship between LMX and helping behavior, as well as the relationship between LMX Mean and team helping behavior such that the effects between them were stronger when LMXD was low rather than high.
This study extended our knowledge how LMX facilitates helping behavior from individual level to multilevel. Moreover, It also explored the multilevel social exchange process between LMX and helping behavior. In practice, managers should improve interpersonal interaction and develop high social exchange quality with members. Moreover, leaders should cultivate positive interpersonal justice climate in the team, furthermore, leaders also should reduce LMXD to avoid the negative consequences.
Increasing research attention has been paid to the influence of loneliness on consumer judgment and decision making, especially lonely people’s attitude to anthropomorphic product. However, past studies are exclusively focused on only one aspect of lonely people’s psychological demands, which cannot fully explain the complexity of the psychological processes underlying their attitudes to anthropomorphic product. Built on previous research in loneliness, this research explores how lonely people form attitude toward anthropomorphic product by taking an integrative perspective, which analyzes the influence of product display on lonely people’s attitude based on self-regulation system theory. This research proposes that when anthropomorphic product and normal product are presented apart, this display format activates lonely consumer’s heighten system and increases their preferences for anthropomorphic product, whereas when these products are presented together, this display format triggers lonely consumer’s balance system and promotes their preferences for normal product. Last but not least, this research identifies a boundary condition of the main effect by examining the moderating role of information type.
Based on three studies, the authors investigated the influence of product display on lonely individual’s attitude to anthropomorphic product. In Study 1, the researchers testified the influence of product display on lonely people’s attitude to anthropomorphic product which constructed an integrative model and verified the main effect. 65 lonely individuals participated in Study 2 which used the relationship between products (substitutive or complementary) to substitute product presentation. The purpose was to further testify the theoretical process underlying the main effect. Study 3 examined the moderating role of information type in the relationship between product display and product attitude.
The results of the present research are three-fold: to start with, product display influences lonely people’s attitude to anthropomorphic product. When products are displayed apart, lonely individuals prefer anthropomorphic product. However, the opposite is true when products are displayed together. Secondly, the relationship between products (substitutive, complementary) can substitute product display (apart, together). This research also examines the moderating effect of information type on the main effect. The results proclaim that when products are displayed apart, ‘to do’ information can promote lonely people’s attitude and purchase intention to anthropomorphic product as compared to ‘to go’ information; and when products are displayed together, this effect will reverse.
These findings enrich the theoretical value of loneliness in three ways: firstly, it focuses on lonely individual’s attitude to anthropomorphic product in an integrative perspective, which reconciles conflicting research findings in this field. In doing so, this research not only identifies the boundary conditions of lonely people’s increased preference for anthropomorphic product, but also investigated how to make this effect stronger by manipulating information type. In conclusion, this research investigates the influence of product display on lonely people’s attitude to anthropomorphic product and provides feasible guideline for companies to employ anthropomorphic strategy appropriately.
It is important to study the underlying mechanisms through which consumers’ desire for touch forms, because it can help online and offline companies to develop effective strategies that can compensate for and satisfy consumers’ desire for touch. Up to date, existing research on why consumers’ desire for touch forms can be categorized into four research perspectives: information processing perspective (consumers show a strong desire for touch to process product-related information), motivational perspective (consumers show a strong desire for touch to solve problems or to experience hedonics), decision-making perspective (consumers show a strong desire for touch to facilitate their decision-making), and innate personality perspective (consumers’ desire for touch is innate and relatively stable). However, none of these perspectives is able to explain why when being in different states of cognitive experience (i.e. encountering threats to personal control and not encountering such threats), the same consumer’s reaction to touch differs. The two-process model of perceived control argues that threats to personal control cause individuals to exert forces and control over environment. While touching a product implies that a consumer can move, hold and grasp the product and exert physical control over it. Thus, the current research proposes that the cognitive experience of low feeling of threats to personal control is the antecedent of consumers’ strong desire for touch. More important, we will also examine the underlying mediation mechanisms and boundary conditions of the proposition above.
Four experiments were conducted to examine whether, why and when threats to personal control would (not) increase consumers’ desire for touch. Experiment 1 investigated the core assumption that after controlling individual differences in desire for touch, consumers’ current desire for touch will be still influenced by an important situational factor, that is, whether they are facing with threats to personal control. The results of Experiment 1 showed that after controlling their scores of Need For Touch, participants who encountered with control threats responded faster to touch-related words than those who did not face control threats, suggesting that low feeling of threats to personal control is an antecedent of consumers’ desire for touch. Experiment 2 further investigated whether consumers’ desire for touch was only affected by control threats. Importantly, this experiment further found that need for control was a mediator, ruling out other alternative explanations. Experiment 3 provided supports to H2 that the main effect of threats to personal control on consumers’ desire for touch was moderated by whether they were offered with an opportunity to strengthen their self-value. Finally, Experiment 4 showed that the moderation effect of strengthening self-value reported by Experiment 3 disappeared when consumers’ self-esteem was low (vs. high).
The cognitive experiential perspective reported by the current research can enrich our traditional understanding on why consumers show a strong desire for touch. Also, this perspective can significantly advance existing research on affirming one’s self-value and research on self-esteem.
“Inaction inertia”, the phenomenon that a person continues forgoing a positive but less attractive opportunity after missing an initial attractive one, has attracted much attention from scholars from various disciplines. A detailed review of the literature reveals that much of the research on inertia effect has focused on the characteristics of opportunities and the relationships among different opportunities. However, few studies have investigated this phenomenon from the characteristics of decision-makers perspective. In line with this view, this paper aims to examine how self-regulatory modes (i.e., locomotion and assessment) of decision-makers influence the “inaction inertia” effect in a consumption context. We propose that consumers with high locomotion mode are more likely to take the second opportunity than consumers with high assessment mode after missing a more attractive opportunity. This effect can be explained by the perception of anticipated regret, which is defined as the tradeoff between the anticipated inaction regret and the anticipated action regret, of consumers. In addition, we propose that the effect is moderated by product types provided in the second opportunity. If the product in the second opportunity is an alternative product that is similar to but somewhat different from that in the first opportunity, the effects of self-regulatory on the likelihood of action will be attenuated.
We conducted three experiments to test the proposed hypotheses. Eighty-seven undergraduate students participated in Study 1 to examine the effect of regulatory mode on the likelihood of taking the second opportunity. In this study, participants read a scenario about missing an opportunity to buy an LED lamp and facing a second less attractive opportunity. We measured participants’ regulatory mode and the likelihood of action, and used linear regression model and ANOVA to analyze the results. Study 2 used a 2 (regulatory mode: locomotion vs. assessment) by 2 (attractiveness difference: large vs. small) between-subjects experimental design with 115 participants to examine how the regulatory mode influenced participants’ likelihood to taking the second opportunity and to investigate the role of anticipated regret in inaction inertia effect. We manipulated participants’ regulatory mode and the attractiveness between the first and the second opportunity. We then used ANOVA to analyze the results and used PROCESS (Hayes, 2013) to test the mediation effect of anticipated regret. To examine how the product type in the second opportunity influences the effect of regulatory mode on the likelihood of action in the second opportunity, a 2 (regulatory mode: locomotion vs. assessment) × 2 (product type: same product vs. alternative product) between-subjects design was adopted. A total of 114 undergraduate students participated in Study 3. We used the same statistical methods as those in Study 2 to test our hypotheses.
The results of Study 1 demonstrated that compared with participants with high assessment mode, participants with high locomotion mode were more likely to take action when encountering the second opportunity. The results of Study 2 showed that when the attractiveness difference between the first and the second opportunity was relative large, participants with high locomotion mode expressed higher likelihood of action than those with high assessment mode, while participants showed no difference in the likelihood of action when the attractiveness difference between two opportunities was relative small. Furthermore, the tradeoff between anticipated inaction regret and anticipated action regret mediated the effect of regulatory mode on likelihood of action. The results in Study 3 indicated that when using the same product in the second opportunity as in the first opportunity, participants with high locomotion mode showed higher likelihood of action than those with high assessment mode. However, when providing the alternative product in the second opportunity, the difference of the likelihood of action between participants with different regulatory mode was attenuated.
The findings of this paper enhance our understanding of inaction inertia effect by investigating how regulatory mode influences the likelihood of action. We found that the tradeoff between the anticipated inaction regret and the anticipated action regret mediates the effects of regulatory mode on the likelihood of action. Moreover, the paper contributes to the regulatory mode theory by extending it to a new consumption context. Finally, the paper provides several managerial implications as well. It provides a new way for marketers to target consumers by identifying their regulatory mode and further to run marketing campaigns based on consumers’ different level of anticipated regrets. In addition, marketers can use an alternative product in the second opportunity that is similar to but somewhat different from that in the missing opportunity to effectively attenuate the inaction inertia for consumers with high assessment mode.
Since Preacher and Kelley (2011) proposed kappa-squared (k2) as a mediation effect size measure, it has become popular in mediation analyses, as shown by its appearance in research literature (e.g., Athay, 2012; Field, 2013). Furthermore, a special on-line calculator for computing kappa-squared also became available, making its use in research practice very convenient. Unfortunately, Wen and Fan (2015) recently demonstrated both logically and mathematically that kappa-squared has fatal flaws in its definition and calculation, which should put an end to its use in mediation analysis. This article evaluates the appropriateness of the current mediation effect size measures, based on the considerations of the expected characteristics of an effect size.
Effect size plays at least two roles in research practice. First, it provides supplemental information that compensates for the limitation of null hypothesis significance testing (NHST). Second, it makes the research findings comparable across studies in which different measures may have been used. For example, in the context of difference analysis involving two groups, the mean group difference is often the quantity of our research interest. When statistically “significant” difference is revealed by NHST, we are informed that the difference between the two group means is statistically different beyond what would be expected as a result of sampling error; but we are not entirely clear about how large the difference is. Primarily for this reason, it has been advocated that an effect size measure be used to supplement the statistical NHST (Fan & Konold, 2010; Wilkinson & the Task Force on Statistical Inference, 1999). Why can’t we directly report the effect (such as the mean group difference) that represents the original quantity of interest? It turns out that the original quantity (e.g., mean group difference) is usually not comparable across studies because different measures across the studies usually have different and arbitrary measurement scales (e.g., 5-point difference on two different tests may have very different meanings). Because of these difficulties, an effect size is often constructed as a scale-free index to represent the original quantity of interest. When the NHST result is supplemented by an effect size, it is more likely that both statistical and practical meanings of an analysis finding can be better understood and conveyed.
To serve its purpose, an effect size should have some basic characteristics, including being scale-free, being monotonic with respect to the effect that it represents, and being independent of sample size. It was the lack of monotonicity that kappa-squared was called into question by Wen and Fan (2015). They showed that the problem of kappa-squared is due to (1) the improper calculation of the maximum possible value of the indirect effect, and (2) mathematically, the maximum possible indirect effect is infinity, implying that the definition of kappa-squared is mathematically incorrect.
Several R2-type effect size measures for mediation effect have been proposed, such as De Heus’s (2012) , MacKinnon’s (2008) , and . But all these measures are not monotonic with respect to the mediation effect. Lachowicz’s (2015) is obviously a monotonically increasing function of the mediation effect in absolute value. However, it is more difficult to understand and explain than the original mediation effect ab itself.
The traditional mediation effect size (the ratio of the indirect effect to the total effect) is not perfect as a mediation effect size by itself. But when accompanied by the total effect and indirect effect in standardized form, it is meaningful for a basic mediation model where the indirect effect ab and the direct effect have the same sign. For inconsistent mediation models where the indirect effect ab and the direct effect have opposite signs, is not appropriate as a mediation effect size measure, and what is a suitable effect size in this situation is still an issue to be addressed in future research.
Mirror neurons are a class of sensorimotor neurons in the monkey premotor and parietal cortices. These neurons have both motor and visual properties: they discharge not only when a monkey performs a goal-directed action, but also when the monkey passively observes a same or similar action performed by another agent. Because the observed action seems to be “reflected”, like in a mirror, these neurons are called mirror neurons. Over the years, due to the restriction of research ethics, the techniques of single-cell electrodes-implanted can not be used in human brain research. Therefore, it was not certain that whether or not there are also mirror neurons in human brain. However, through the studies of brain image such as TMS, PET, EEG, MEG and FMRI, it is now certain that there are some brain areas which have same or similar functions as mirror neurons. These brain areas are called mirror neuron system. In this article, the significances of mirror neurons and human mirror neuron systems are discussed in depth. It states that: (1) Just because of the mirror mechanism that can match action observation with action execution, the observer’s neural network involved in action execution will be activated by just seeing others’ actions. Mirror neuron systems project the perceived actions back onto one’s own motor representation of similar actions, the individual will automatically and unconsciously perform a dynamic simulation of the observed action in one’s own motor system. This simulation, in turn, allows the individual to create directly an embodied understanding of the observed person’s thoughts, feelings and intention of behavior. (2) The fact that mirror neurons fire both in action execution and in action observation shows that The mind and body are not two kinds of substance, but an integrated one. Our body's physical and physiological processes and our mental processes, in the essence, are different respects of the same activity of adaptation. They are one activity instead of two. it seems that mirror neurons bridge the gap between mind and body. It opens a new vision for reconsidering the mind-body relationship and provide a strong neurophysiological support for the unity of mind and body. (3) Mirror neurons unify action perception and action execution, enable us not only to understand the intentions and actions of others, but to build social networks, allowing us to feel another’s emotions such as joys and pains as our own. By means of the shared neural underpinnings, others’ intention, feelings and emotions become our own. Thus, mirror neurons act as a “neural bridge” between different individuals in social communication.