Table 1.
Cognitive tasks performed in pigs
| Task | Tested cognitive ability/abilities | N | Sex | Reinforcer | Age (or weight) | Food restriction schedule | Author |
|---|---|---|---|---|---|---|---|
| Classical conditioning tasks | |||||||
| Appetitive learning | |||||||
| Conditioned salivary response | Association learning | 2 | F | Food | 6 weeks | Unknown | Moore and Marcuse (1945) |
| Aversive learning | |||||||
| Conditioned aversive response | Association learning | 50–64 | ? | – | 75–135 days | - | Noble and Adams (1963) |
| Operant conditioning tasks | |||||||
| Multiple choice apparatus | Ideational problem solving | 2 | B/F | Food | 2 months | Unknown | Yerkes and Coburn (1915) |
| Appetitive learning | |||||||
| Conditioned suppression of operant responding | Learning ability | 12 | B/F | Food | 2–4 months | Unknown | Baldwin and Stephens (1973) |
| Lever pressing | Hierarchy behavior and social learning | 64 | B/F | Commercial pellets | 20–40 kg | Abstention 24 h pre-testing | Baldwin and Meese (1979) |
| Panel switching | Preference testing | 66 | B/F | Sweetened water | 2–4 months | Fed 1x daily | Kennedy and Baldwin (1972) |
| Lever pressing | Learning ability | 84 | M/F | Unknown | 15–17 weeks | Ad libitum | Sneddon et al. (2000) |
| Lever pressing | Measure of motivation | 6 | F | Unknown | 4.5 months | Fed 2x daily | Ferguson et al. (2009) |
| Temporal response differentiation training | Time perception | 3 | F | Unknown | 4.5 months | Fed 2x daily | Ferguson et al. (2009) |
| Incremental repeated acquisition | Learning ability | 3 | F | Unknown | 4.5 months | Fed 2x daily | Ferguson et al. (2009) |
| Discrimination reversal test | Reversal learning | 34 | M/F | Food | >35 days | Unknown deprivation schedule | Lien and Klopfer (1978) |
| Reversal learning | Learning ability | 60 | B/F | Commercial pellets | 8 weeks | Ad libitum | Bolhuis et al. (2004) |
| T-maze | Discrimination learning | 4 | F | Food | 21–42 days | Unknown | Tanida et al. (1991) |
| Y-maze | Discrimination/recognition learning | 5 | M | Raisins | 8 weeks | Unknown | Tanida and Nagano (1998) |
| Y-maze | Discrimination/recognition learning | 6 | F | Raisins | 8 weeks | Fed 2x daily | Koba and Tanida (1999) |
| Standard human approach test | Association learning | 24–36 | F | Commercial finisher ration | 17–23 weeks | Fed 1x daily | Hemsworth et al. (1996) |
| Discrimination learning | Spatial, visual and olfactory learning | 4 | B | Milk-bone dog biscuits | 2.5–3 years | No restrictions | Croney et al. (2003) |
| Eight-arm radial maze | Discrimination learning and memory | 53 | Unknown | Milk replacer | 3 days | Fed 4x daily | Wang et al. (2007) |
| Set-shifting procedure | Spatial, visual, reversal and extra-dimensional learning | 16 | M/F(c) | M&M chocolates | 4 months | 70% of daily ration | Moustgaard et al. (2004) |
| Conditional go/no-go task | Learning ability | 14 | M/F(c) | M&M chocolates | 5–5.5 months | 70% of daily ration | Moustgaard et al. (2005) |
| Food covering | Discrimination learning (non-visual) | 20–25 | F | Milk replacer | 1–12 days | Unknown | Friess et al. (2007) |
| Glass barrier task | Problem-solving skills | 20–25 | F | Milk replacer | 1–12 days | Unknown | Friess et al. (2007) |
| Aversion learning | |||||||
| Avoidance conditioning | Learning ability | 84 | B/F | Unknown | 40/80/150 days | Unknown | Kratzer (1969) |
| Avoidance conditioning | Learning ability | 50 | M/B/F | Light | 3–6 months | Unknown | Chaput et al. (1973) |
| Avoidance conditioning | Excitement and emotionality | 120 | Unknown | Inapplicable | 21 days | Unknown | Hammel et al. (1975) |
| Avoidance conditioning | Learning ability/Ability of response inhibition | 18 | M | Inapplicable | 3 weeks | Low calorie/low protein/ad. lib. | Barnes et al. (1969) |
| Preference test | Time perception and anticipation of future events | 12 | F(p) | Commercial pellets | 8 months | Restricted (unknown %) | Spinka et al. (1998) |
| Spatial learning and memory tasks | |||||||
| Alley mazes | |||||||
| Three-choice point water maze | Spatial learning and memory | 120 | Unknown | Unknown | 45 days | Unknown | Hammel et al. (1975) |
| Adjusted Hebb–Williams maze | Learning ability and (long-term) memory | 48 | B/F | Commercial pellets | 11/20 weeks | Abstention 12 h pre-testing | Jong et al. (2000) |
| Spatial maze | Spatial learning and memory | 27 | B/F | Sow and litter | 5 days | Ad libitum | Siegford et al. (2008) |
| Modified Morris water maze | Spatial learning and memory | 27 | B/F | A dry location (platform) | 14 days | Ad libitum | Siegford et al. (2008) |
| Free-choice mazes | |||||||
| Foraging arena | Spatial learning and memory | 8 | M | Unknown | 48.06 ± 1.72 kg | 80% of daily ration | Mendl et al. (1997) |
| Eight-arm radial maze | Spatial learning and memory | 10 | M | Sow rolls | 30–35 kg | 70% of daily ration | Laughlin et al. (1999) |
| Multi-room maze | Learning abilities | 27 | F | Apple | 3–4 months | Unknown | Hagl et al. (2005) |
| Eight-arm radial maze | Spatial learning and memory | 20 | M | Sow rolls | 30–35 kg | 75% of daily ration | Laughlin and Mendl (2000) |
| Eight-arm radial maze | Spatial learning and memory | 16 | M | Sow rolls | 10–12 weeks | 80% of daily ration | Laughlin and Mendl (2004) |
| Spatial arena | Spatial learning | 84 | M/F | Unknown | 15–17 weeks | Ad libitum | Sneddon et al. (2009) |
| Cognitive holeboard | Spatial learning and memory | 20 | F | Chocolate raisin | 13 weeks | Restricted (unknown %) | Arts et al. (2009) |
| Restricted retrieval choice test | Spatial discrimination and memory | 9 | F | Sow rolls | 28.8 kg ± 2.42 | 80% of daily ration | Held et al. (2005) |
| T-Maze (delayed non-match to sample task) | Spatial learning and memory | 8 | B | Mini-pellets in water | 12–14 months | 70% of daily ration | Nielsen et al. (2009) |
| Recognition tasks | |||||||
| Object recognition | |||||||
| Spontaneous object recognition | Object recognition memory | 8 | M | – | 13 months | Restricted (unknown %) | Moustgaard et al. (2002) |
| Spontaneous object recognition | Object recognition memory | 16 | M | – | 12–14 months | Fed 2x daily | Kornum et al. (2007) |
| Spontaneous object recognition | Object recognition memory | 64 | B/F | – | 27 days | Unknown | Gifford (2005) |
| (Modified) spontaneous object recognition | Object recognition memory | 36 | B/F | – | 35 days | Ad libitum | Gifford et al. (2007) |
| Social recognition | |||||||
| Social recognition based on olfactory cues | Social discrimination/recognition learning | 2 | Unknown | Commercial pellets | 6–9 months | Unknown | Meese et al. (1975) |
| Y-maze | Social discrimination/recognition learning | 32 | M | – | 6–7 weeks | Ad libitum | Kristensen et al. (2001) |
| Habituation–dishabituation procedure | Social discrimination | 22 | F | – | 10 weeks | Ad libitum | Mendl et al. (2002) |
| Y-maze | Social discrimination/recognition learning | 12 | F | Raisins | 6 weeks | Ad libitum | McLeman et al. (2005) |
| Social recognition test | Social discrimination/recognition learning | 120–132 | M/F | – | 11–13 days | Ad libitum | De Souza et al. (2006) |
| Y-maze | Social discrimination | 12 | F | Raisins | Juvenile | Removed between 8am–12 pm and 13 pm–17 pm | McLeman et al. (2008) |
| Observational learning | |||||||
| ‘Informed forager’ paradigm | Exploitation of knowledge of others | 16 | F | Unknown | >29.87 kg | 70% of daily ration | Held et al. (2000) |
| Adapted Guesser–Knower experiment | Exploitation of knowledge of others | 18 | F | Commercial pellets | Juvenile | 70% of daily ration | Held et al. (2001) |
| Awareness | |||||||
| Mirror Test | Object/information use | 19 | M/F | Food | 4–8 weeks | Ad libitum | Broom et al. (2009) |
Task Name of the experiment performed. Tested cognitive ability/abilities Type of cognition measured during the experiment. N Amount of animals applied during the experiment. Sex: F female/sow, M male/intact boar, B castrated male/barrow. Reinforcer Type of reinforcement applied. Age Age of animals at the beginning of the experiment, or if unknown, weight of animal at the beginning of the experiment. Food restriction schedule If applied, type of restriction schedule. Author Researcher(s) performing the experiment