Table 2.

Description of measures used in included studies.

Type of test	Test + meaning of test result
Physiology (American Psychological Association, 2019b)	Sympathetic Nerve Activity • Under stress, the “fight or flight” response is activated in the body by the sympathetic nervous system (SNS). The SNS acts to release cortisol into the blood. SNS activity can be measured by heart rate variability, via the R-R interval (time duration between two consecutive R waves as measured on an electrocardiogram) (Park et al., 2008). High frequency elements act as a marker of parasympathetic activity (calm); a formula using low and high frequency elements acts as a marker of sympathetic activity (stress) (Lee et al., 2011). Salivary Cortisol Levels • Cortisol is a naturally-occurring hormone that is released under stress. When cortisol increases, the body responds by increasing heart rate, blood pressure, muscle tension, and respiratory rate. Levels of cortisol can be measured via mouth, with a swab or pipette that absorbs saliva. Heart Rate • Heart rate spikes when cortisol levels increase (under stress), and can be measured manually or remotely via monitors. Blood Pressure • Blood pressure spikes when cortisol levels increase (under stress) as blood vessels dilate to get more blood to the body; this is measured via a cuff. Secretory Immunoglobulin A • A marker of stress, as measured via saliva (Fan et al., 2008; Benham et al., 2009).
Affect	EFI: Exercise-Induced Feeling Inventory (Gauvin and Rejeski, 1993) • Self-report questionnaire to assess positive and negative affect • 12 questions to assess current feelings (calm, energetic, enthusiastic, fatigued, happy, peaceful, refreshed, relaxed, revived, tired, upbeat, worn out) • All items scored on a 5-point Likert scale (“do not feel” to “feel very strongly”) NMS: Negative Mood Scale (Scott et al., 2001) • A measure of immediate and/or persistence affective responses • 19 items measured (e.g., worried, anxious, sad, angry, irritable, rushed) • All items scored on a 5-point scale (“not at all” to “very much”) OHS: Overall Happiness Scale (Campbell et al., 1976) • A measure of quality of life • All items scores on a 100-point thermometer-like graph (“very unhappy” to “very happy”) PANAS: The Positive and Negative Affect Schedule (Watson et al., 1988; Crawford and Henry, 2010) • Validated self-report questionnaire to assess positive and negative affect • Mostly used in research settings • 10 questions for positive affect (active, alert, attentive, determined, excited, enthusiastic, inspired, interested, proud, strong); 10 for negative affect (afraid, ashamed, distressed, guilty, hostile, irritable, jittery, nervous, scared, upset). • All items scored on a 5-point Likert scale (“not at all” to “extremely”) POMS: Profile of Mood States (Heuchert and McNair) • Validated self-report questionnaire to assess mood disturbance • Measures seven dimensions of fluctuating feelings and affect states [anger-hostility (AH), confusion-bewilderment (C), depression-dejection (D), fatigue-inertia (F), tension-anxiety (TA), vigor-activity (V)] • Long form has 65 questions; short form has 35 questions • All items scored on a 5-point Likert scale (“not at all” to “extremely”) PSS: Perceived Stress Scale (Cohen, 1994) • Validated self-report questionnaire to assess perceived stress • 10 items that measure feeling for stress over the last month (using descriptors such as unpredictable, uncontrollable, and overloaded) • All items scored on a 5-point scale (“never” to “very often”); higher score indicates higher perceived stress Refreshed (Mackay et al., 1978) • (It appears that this measure might come from Mackay's scale that was published in 1978. The scale uses 30 adjectives to allow a respondent to sell assess stress and arousal. It is unclear if the full scale was used, or just questions that relate to feelings of being refreshed.) SD: Semantic Differential (Summers, 1970) • Pairs of adjectives presented (i.e., comfortable–uncomfortable, soothed—aroused, natural–artificial) • Respondents plot their “position” on a scale between the two adjectives; 3-, 5-, or 7-point scale can be used SCL-90-R: Symptom Checklist-90-Revised (Derogatis, 1994) • Validated self-report tool that evaluates a range of psychological problems and symptoms of psychopathology • Can be used in research or in clinical setting; good for measuring change in symptoms, including depression and anxiety • 90 questions in 9 symptom dimensions (anxiety, depression, hostility, interpersonal sensitivity, obsessive-compulsive, paranoid ideation, phobic anxiety, psychoticism, somatization scored on a 5-point scale STAI: The State-Trait Anxiety Inventory (American Psychological Association, 2019a) • Measure of trait and state anxiety • Can be used in research (measure of distress) or in clinical setting (diagnose anxiety) • 20 items measured for trait anxiety (e.g., tension, worry, calm, secure); 20 items measured for state anxiety (e.g., worried too much, content, steady person) • All items scored on a 4-point scale (“almost never” to “almost always”) • Higher score means higher anxiety ZIPERS: Zuckerman Inventory of Personal Reactions (Zuckerman, 1977) • Validated self-report questionnaire to assess feelings and reactions • 12 measures in five domains (attentiveness, anger/aggression, fear, positive affect, sadness). • All items scored on a 5-point scale (“not at all” to “very much”) • A sensitive measure in previous experimental research on the relative restorative potentials of natural and urban environments RRQ: Reflection Rumination Questionnaire (Trapnell and Campbell, 1999) • Two scales that measure rumination and reflection • 12 items measured for rumination (e.g., “My attention is often focused on aspects of myself I wish I'd stop thinking about”) • All items scored on a 5-point scale (“strongly disagree” to “strongly agree”) • Higher means of the sum of scores indicate higher degrees of rumination. Self-Reports: (non-validated measures) • Comfort, Calm, Positive Feeling, Relaxation, Self-awareness
Attention	NCPCT: Necker Cube Pattern Control Test (De Young, 2016; Zealand) • Test of capacity to direct mental effort, the ability to inhibit one response over another. When placed under prolonged demand, the ability to direct mental focus diminishes; this decreases mental effectiveness. • Participants view a sketch of a 3-D cube, and note (press the spacebar) when they see one orientation vs. the other. After a baseline measure, participants try to control seeing one perspective vs. another, and note when the orientation shifts. A lower score (over 30 s) shows greater attention. Backwards Digit-Span Task (Berman et al., 2008) • Participants hear sequences of digits and are asked to repeat them in reverse order. • Sequences can vary in length (three to nine digits were used in noted study) • Correct sequences were scored the same, independent of sequence length • The backwards digit-span task depends on directed-attention abilities because participants must move items in and out of their attentional focus which is a major component of short-term memory. SST: Symbol Substitution Test (Johansson et al., 2011) • A symbol substitution test requires sustained directed attention. • A subject writes numbers into a series of blanks, each of which is paired with one of nine symbols. The appropriate number for a symbol is indicated by a key. • After a practice trial, the subject is given 60 s to fill in as many of the 110 available blanks as possible. The score is the number of correctly assigned numbers. Memory-Loaded Search Task (Hartig et al., 2003) • A test of attention • Subjects search lines of letters for five target letters given at the beginning of each line. • Subjects memorize the five given targets, and then search through one line of text, once, to find the targets. • Over a 10-min period, subjects are encouraged to go quickly, but to be accurate. • Task is scored on accuracy: percent of target letters identified, and on speed: number of letters identified. Accuracy × Speed gives final score.