Table 1.
Possible aspects of the tasks that are ‘common’ in common currency tasks—for consideration when designing new tasks
| Common aspects | Type of validity | Notes |
|---|---|---|
| Demographics of sample | Face/construct | Many animal studies only use males [71]—is this appropriate for the research question? Are humans only recruited if they fit into certain demographics (age, medication)? |
| Developmental stage | Face/construct | Is the same developmental stage used in both human and animal research? e.g. adolescent vs adult |
| Task difficulty | Construct | Does the task need to be simpler for animals to achieve the same level of performance? Do overtrained animals perform better than humans? |
| Task duration | Face/construct | Do different species need different task durations? i.e. do humans get bored faster/produce more varied behaviour so more data points are needed for accurate inference? Do animals need many short sessions of a task, whereas humans can perform the task in one longer session? |
| Motivation | Construct | Are animals water restricted to maximise their desire for (water) reward? Are humans reimbursed more for good performance? |
| Training | ||
| Instructed | Face/construct | Are the instructions verbal? |
| Overtraining | Face/construct | Animals are frequently overtrained on tasks, whereas humans are usually not |
| Stimulus presentation | ||
| Modality | Face/construct | Visual, aural? Would construct validity be achieved better if stimuli are different between species? |
| Actual stimuli | Face/construct | E.g. tones may be adjusted for different species’ hearing ranges |
| Response | Face/construct | E.g. do animals and humans both press buttons, or do animals enter a nose-poke? |
| Feedback | ||
| Classification | Face/construct | Often, animals receive primary reinforcers such as sucrose or electrical shocks, and humans receive points or money |
| Actual feedback | Face/construct | Even if both primary reinforcers, feedback may still differ: e.g. white noise in humans, and electric shocks in animals |
| Strategy | Construct | Are animals and humans using the same ‘strategy’ to complete the task? For example, animals and humans may rely to different extents on spatial strategies in the Morris water maze and the virtual-reality human equivalent [16] |
| Data preprocessing | Construct | Is data quality assessed in the same way between species? Are data cleaned in the same way? |
| Analysis | Construct | Are the primary outcome measures the same? Are they calculated in the same way? |
| Behavioural performance | Construct | Is behavioural performance (e.g. patterns of accuracy) similar between species? |
| Neural basis | Construct | Are homologous brain areas and circuits implicated in the performance of this task between species? |
| Sensitivity to symptoms | Face/construct/predictive | Is behaviour on the task sensitive to psychiatric symptoms, e.g. do animal models of anhedonia demonstrate a measurable change from healthy animals in the same way anhedonic humans perform differently to healthy controls? |
| Effects of interventions | Predictive | Do pharmacological agents have the same effects on both human and animal behaviour/neural activity in the task? |