Concerns have been growing about the veracity of psychological research. Many findings in psychological science are based on studies with insufficient statistical power and nonrepresentative samples, or may otherwise be limited to specific, ungeneralizable settings or populations. Crowdsourced research, a type of large-scale collaboration in which one or more research projects are conducted across multiple lab sites, offers a pragmatic solution to these and other current methodological challenges. The Psychological Science Accelerator (PSA) is a distributed network of laboratories designed to enable and support crowdsourced research projects. These projects can focus on novel research questions, or attempt to replicate prior research, in large, diverse samples. The PSA’s mission is to accelerate the accumulation of reliable and generalizable evidence in psychological science. Here, we describe the background, structure, principles, procedures, benefits, and challenges of the PSA. In contrast to other crowdsourced research networks, the PSA is ongoing (as opposed to time-limited), efficient (in terms of re-using structures and principles for different projects), decentralized, diverse (in terms of participants and researchers), and inclusive (of proposals, contributions, and other relevant input from anyone inside or outside of the network). The PSA and other approaches to crowdsourced psychological science will advance our understanding of mental processes and behaviors by enabling rigorous research and systematically examining its generalizability.

Concerns have been growing about the veracity of psychological research. Many findings in psychological science are based on studies with insufficient statistical power and nonrepresentative samples, or may otherwise be limited to specific, ungeneralizable settings or populations. Crowdsourced research, a type of large-scale collaboration in which one or more research projects are conducted across multiple lab sites, offers a pragmatic solution to these and other current methodological challenges. The Psychological Science Accelerator (PSA) is a distributed network of laboratories designed to enable and support crowdsourced research projects. These projects can focus on novel research questions, or attempt to replicate prior research, in large, diverse samples. The PSA’s mission is to accelerate the accumulation of reliable and generalizable evidence in psychological science. Here, we describe the background, structure, principles, procedures, benefits, and challenges of the PSA. In contrast to other crowdsourced research networks, the PSA is ongoing (as opposed to time-limited), efficient (in terms of re-using structures and principles for different projects), decentralized, diverse (in terms of participants and researchers), and inclusive (of proposals, contributions, and other relevant input from anyone inside or outside of the network). The PSA and other approaches to crowdsourced psychological science will advance our understanding of mental processes and behaviors by enabling rigorous research and systematically examining its generalizability.

Thermodynamic parameters describing the phage 434 Cro protein have been determined by calorimetry and, independently, by far-UV circular dichroism (CD) measurements of isothermal urea denaturations and thermal denaturations at fixed urea concentrations. These equilibrium unfolding transitions are adequately described by the two-state model. The far-UV CD denaturation data yield average temperature-independent values of 0.99 ( 0.10 kcal mol -1 M -1 for m and 0.98 ( 0.05 kcal mol -1 K -1 for ∆C p,U , the heat capacity change accompanying unfolding. Calorimetric data yield a temperatureindependent ∆C p,U of 0.95 ( 0.30 kcal mol -1 K -1 or a temperature-dependent value of 1.00 ( 0.10 kcal mol -1 K -1 at 25°C. ∆C p,U and m determined for 434 Cro are in accord with values predicted using known empirical correlations with structure. The free energy of unfolding is pH-dependent, and the protein is completely unfolded at pH 2.0 and 25°C as judged by calorimetry or CD. The stability of 434 Cro is lower than those observed for the structurally similar N-terminal domain of the repressor of phage 434 (R1-69) or of phage λ (λ 6-85 ), but is close to the value reported for the putative monomeric λ Cro. Since a protein's structural stability is important in determining its intracellular stability and turnover, the stability of Cro relative to the repressor could be a key component of the regulatory circuit controlling the levels and, consequently, the functions of the two proteins in vivo.An understanding of the physical interactions underlying the structure, folding, and function of a protein requires a complete thermodynamic description of its conformational stability. Such a description relies on quantitative analyses of thermally or chemically induced folding-unfolding transitions (monitored by calorimetry or spectroscopically), followed by a data extrapolation to given conditions of temperature, pH, etc. To extrapolate thermal denaturation data, the change in heat capacity (∆C p,U ) and its temperature dependence must be known. These are best determined by calorimetry, although other methods have also been developed. Extrapolation of data from chemical denaturation (e.g., urea and guanidine hydrochloride) is based either on the linear free energy model (LEM) 1 found to be valid for a number of proteins (1, 2) or on the denaturant-protein binding model (DBM) (3, 4). Combined analyses of chemical and thermal denaturation data which assume a temperatureindependent ∆C p,U and the thermodynamic equivalence of thermally and chemically denatured states have been reported for various proteins (2,(5)(6)(7)(8)(9)(10)(11)(12).The conformational stability and the principal thermodynamic parameters (∆G U , ∆H U , ∆S U , T m , and ∆C p,U ) which describe the folding transitions of bacteriophage 434 Cro protein are examined here. In vivo, Cro and the repressor proteins regulate the switch between phage lysis and lysogeny by sequence-specific DNA binding (13). 434 Cro has several properties that are desirable for physical studie...