You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Interpersonal Synchrony: A Survey of Evaluation Methods across Disciplines 
Chapter Title:  CONCLUSION 
1. Abstract of Cited Paper (BIB001):  Entrainment has played a crucial role in analyzing marital couples interactions. In this work, we introduce a novel technique for quantifying vocal entrainment based on Principal Component Analysis (PCA). The entrainment measure, as we define in this work, is the amount of preserved variability of one interlocutor’s speaking characteristic when projected onto representing space of the other’s speaking characteristics. Our analysis on real couples interactions shows that when a spouse is rated as having positive emotion, he/she has a higher value of vocal entrainment compared when rated as having negative emotion. We further performed various statistical analyses on the strength and the directionality of vocal entrainment under different affective interaction conditions to bring quantitative insights into the entrainment phenomenon. These analyses along with a baseline prediction model demonstrate the validity and utility of the proposed PCA-based vocal entrainment measure. Index Terms: vocal entrainment, couples therapy, behavioral signal processing, principal component analysis 
2. Abstract of Cited Paper (BIB002):  Objective: The authors quantified nonverbal synchrony—the coordination of patient's and therapist's movement—in a random sample of same-sex psychotherapy dyads. The authors contrasted nonverbal synchrony in these dyads with a control condition and assessed its association with session-level and overall psychotherapy outcome. Method: Using an automated objective video analysis algorithm (Motion Energy Analysis; MEA), the authors calculated nonverbal synchrony in (n = 104) videotaped psychotherapy sessions from 70 Caucasian patients (37 women, 33 men, mean age = 36.5 years, SD = 10.2) treated at an outpatient psychotherapy clinic. The sample was randomly drawn from an archive (N = 301) of routinely videotaped psychotherapies. Patients and their therapists assessed session impact with self-report postsession questionnaires. A battery of pre- and postsymptomatology questionnaires measured therapy effectiveness. Results: The authors found that nonverbal synchrony is higher in genuine interactions contrasted with pseudointeractions (a control condition generated by a specifically designed shuffling procedure). Furthermore, nonverbal synchrony is associated with session-level process as well as therapy outcome: It is increased in sessions rated by patients as manifesting high relationship quality and in patients experiencing high self-efficacy. Higher nonverbal synchrony characterized psychotherapies with higher symptom reduction. Conclusions: The results suggest that nonverbal synchrony embodies the patients' self-reported quality of the relationship and further variables of therapy process. This hitherto overlooked facet of therapeutic relationships might prove useful as an indicator of therapy progress and outcome.

Literature Review:
The current essay attempted to show that the assessment of interactional synchrony bears challenging questions at the crossover of several research domains. Psychologists' coding methods and noncomputational evaluation tools are essential for engineers to identify the relevant signals, validate machine-learning techniques to automatically detect occurrence of synchrony, and model interactive patterns. New socially adapted interfaces could emerge from a better analysis of these social mechanisms. In return, psychologists could benefit from computational methods developed to study synchrony. Such methods could provide automatic and objective tools to study interactive abilities in several psychiatric conditions, such as depression and autism. Although few studies are currently available in this specific field, they appear to be very promising (couple therapy BIB002 , success in psychotherapy BIB003 , mother-infant interaction BIB001 ). Another great potential lies in the opportunity to build robots or virtual agents with interactive abilities. Indeed, such a setting allows control of the variables and testing of different settings and behaviors. Such manipulations can benefit both engineers and clinicians and can lead to a better understanding of the underlying mechanism of social interactions. . For more information on this or any other computing topic, please visit our Digital Library at www.computer.org/publications/dlib.