Table 1. Studies of Effort-Based Decision Making in Schizophrenia

Reference and sample	Paradigm	Patient vs control differences?	Association with negative symptoms?	Association with functioning?	Association with other symptoms?	Association with cognition?
Physical effort: hand grip
Hartmann et al33 : 31 SCZ/ SAD mixed in- and outpatients; 20 controls	Handgrip task: 4 effort levels (with individual titration) and 5 reward levels. Dependent variables: Computed indifference points for each effort level and overall area under the curve (AUC): Paid out 5 random trials	N/A	Yes: Continuous and categorical Total symptoms: N/A Experiential symptoms: AUC correlated with BNSS and SANS apathy factors. Using median split on BNSS apathy factor and 4 indifference points, found significant group and effort level effects with trend-level interaction: high apathy group showed greater discounting than low apathy and control groups. Expressive symptoms: No associations	Yes: Lower Personal and Social Performance Scale correlated with AUC	No: PANSS, CDSS	No: Composite of verbal learning, verbal and visual working memory, processing speed, planning, and semantic/ phonemic fluency tests
Docx et al32 : 40 SCZ (status not specified); 39 controls	Handgrip task: 6 effort levels (with individual titration) and reward adjusted to identify indifference points. Separate choice and execution blocks. Told would receive cash bonus based on performance—all actually paid small bonus	No. Groups comparable on indifference points	No Total symptoms: SANS total median split; No difference for indifference points Experiential symptoms; No continuous or categorical differences for anhedonia and avolition subscales Expressive symptoms: N/A	N/A	N/A	No: Composite or working memory, attentional vigilance, and processing speed tasks
Physical effort: Button pressing
Fervaha et al28 : 16 SCZ outpatients; 16 controls	Effort Expenditure for Reward Task: 2 reward levels and 3 probability levels (12, 50, 88%). Button presses required for hard and easy tasks | individually titrated. 20min time limit. Payout information not specified. Dependent variable: percent hard choices	Yes: Group X reward and Group X probability interactions, no 3-way interaction. For low reward trials, patients selected more hard choices at 12% but not at 50 or 88%; for high reward trials, patients selected less hard choices at 50 and 88% but not at 12%	No Total symptoms: SANS and Apathy Evaluation Scale- clinician not associated with hard choices in the 50% or 88% conditions. Experiential symptoms: N/A Expressive symptoms: N/A	No: Quality of Life Scale— abbreviated	No: SAPS	No: MCCB
Gold et al31 : 44 SCZ/SAD primarily outpatients; 36 controls	Balloon Effort Task: 5 reward levels and 2 probability levels (50, 100%). Button presses required for hard and easy tasks not individually titrated. Participants told they would receive cash bonus based on performance and were given a standard bonus amount. Dependent variable: percent hard choices	Yes: Group X probability interaction, trend for group x reward interaction, no 3-way interaction. Patients selected fewer hard tasks than controls at the highest reward levels in the 100% condition, but no group differences at 50%	Yes: Categorical Total symptoms: Median split on BNSS Total score - high negative symptoms group had fewer hard choices than controls at highest reward level in 100% condition (no differences between low negative symptoms group and controls). Correlational analyses for BNSS total were nonsignificant. Experiential symptoms: Correlational and median split analyses for BNSS avolition and anhedonia items were nonsignificant. Expressive symptoms: N/A	N/A	No: BPRS	Yes: Higher MCCB scores correlated with more hard choices at highest reward levels
Barch et al29 : 59 SCZ/SAD outpatients; 39 controls	Effort Expenditure for Rewards Task: 4 reward levels and 2 probability levels (50%, 88%.); Button presses for hard and easy tasks not individually titrated. 15 minute time limit. Two random trials rewarded. Dependent variable: percent hard choices	Yes. Group X reward and Group X probability interactions, no 3-way interaction. Patients chose fewer hard tasks than controls at higher reward and probability levels	Yes: Continuous Total Symptoms: N/A Experiential Symptoms: Items from SANS and BNSS combined to create composite Avolition and Anhedonia scales. Higher avolition correlated with fewer hard choices in 88% condition and with smaller increases in hard choices from 50–88% conditions Expressive symptoms: N/A	Yes: Better SLOF community and work functioning associated with more hard choices in 88% and in highest reward level	Yes: SAPS positive and disorganization symptoms	N/A
Treadway et al30 : 12 SCZ outpatients; 15 controls	Effort Expenditure for Rewards Task: 4 reward levels and 3 probability levels (12%, 50%, 88%.). Button presses for hard and easy tasks not individually titrated. Time limit and payout information not specified. Dependent variable: percent hard choices	Yes: Group X reward and Group X probability interactions, no 3-way interaction. Patients chose fewer hard tasks than controls at higher reward and probability levels	Yes: Continuous Total Symptoms: Trend for correlation between higher SANS and lower scores on a summary index of ability to incorporate reward and probability information. Experiential symptoms: N/A Expressive symptoms: N/A	N/A	N/A	N/A
Cognitive effort
Wolf et al34 : 41 SCZ outpatients; 37 controls	Cognitive effort progressive ratio task. Seven sets of trials (identify which of 2 numbers is bigger) at each of 3 reward levels. Number of correct responses to receive a reward increased within each successive trial set for each reward levels. Participants paid what they earn. Dependent variable: Break point	Yes: Patients had lower breakpoints than controls	Yes: Continuous Total Symptoms: N/A Experiential Symptoms: Higher CAINS amotivation items correlated with lower breakpoint. Expressive Symptoms: No associations	N/A	N/A	N/A
Gold et al35 : 83 SCZ/SAD outpatients; 71 controls across 3 experiments	Series of studies using different version of the Demand Selection Task in Experiments (implicit selection task for stimuli associated with frequent [hard choice] or infrequent [easy choice] set-shifting demands): (1) standard instructions, (2) more explicit instructions, (3) further instruction and parameter changes. No monetary rewards involved. Dependent variable: percent hard choices	Mixed: Experiments: (1) No effort related effects for either group, (2) Less effort avoidance in patients, (3) No group differences in effort avoidance	No Total symptoms: BNSS and SANS total scores not associated with effort aversion in each experiment and in combined sample. Experiential Symptoms: BNSS, SANS avolition and anhedonia subscales not associated with effort aversion in each experiment and in combined sample. Expressive symptoms: N/A	N/A	No: BPRS	Yes: Higher MCCB and WASI correlated with more effort discounting in the total combined sample

Notes: BNSS, Brief Negative Symptom Scale; BPRS, Brief Psychiatric Rating Scale; CDSS, Calgary Depression Scale for Schizophrenia; CAINS, Clinical Assessment Interview for Negative Symptoms; MCCB, MATRICS Consensus Cognitive Battery; N/A, not assessed; PANSS, Positive and Negative Symptom Scale; SAD, schizoaffective disorder; SANS, Scale for the Assessment of Negative Symptoms; SCZ, schizoaffective disorder; SLOF, Specific Levels of Functioning Scale; WASI, Wechsler Abbreviated Scale for Intelligence.