Exploring Memory and Perception in Animals

1. PSY 402 Theories of Learning Chapter 8 – Stimulus Control Space and Time in Humans and Animals

2. Visual Perception in Pigeons • Pigeons recognize objects in the same way as humans do. • Biederman’s geons are recognized by both humans and pigeons. • Geon (geometric ion) – a primitive component of an object. • When geons were preserved, recognition was better than when they were disrupted.

3. 8.16 Stimuli used in the experiment by Van Hamme et al Left & middle have different lines but same geons Right has same elements in a different order, with geons disrupted. Best responding Worst responding

4. Conjunction of Features • Both pigeons and humans experience “pop out” of single features, but not for the conjunction of features (combined features). • Treisman’s studies were replicated: • Conjoined features require additional attention and more processing for pigeons & humans. • Peck location was determined using a touchscreen.

5. 8.17 Examples of computer stimuli presented to pigeons by Cook (Part 1)

6. 8.17 Examples of computer stimuli presented to pigeons by Cook (Part 2)

7. 8.17 Examples of computer stimuli presented to pigeons by Cook (Part 3) Less popout with conjoined features.

8. Same-Different Detection • Pigeons can make decisions based on variability of a pattern. • Pigeons were trained to make same-different discriminations: • Rows need not be perfectly aligned (straight). • The number of items in the array doesn’t matter. • Entropy (number of different items) is important – 8 items are needed for accuracy. • Is detection based on texture or evaluation?

9. 8.18 “Same” and “different” displays used in the experiment by Wasserman et al

10. Attention Processes • Differential reinforcement of different aspects of a stimulus causes pigeons to pay more or less attention to them (dot color vs tone). • Attention to the features of cryptic prey increases with reinforcement and decreases with split attention. • Priming improves attention to important features in runs of trials, but disappears as the task becomes automatic.

11. 8.1 Sample of moths from the beginning and end of the experiment (Part 2) Examples of cryptic prey

12. 8.19 Attentional priming

13. Pigeon Working Memory • Pigeon working memory is very short. • Delayed matching to sample task (DMTS) – performance is at chance with a 6 sec delay. • Increased exposure to the sample improves performance. • Practice improves performance (60 sec retention) • Interference hurts performance – changing anything before or after the task interferes.

14. 8.20 Pigeon working memory in the delayed matching-to-sample (DMTS) task Stimulus stays on longer with more pecks.

15. Rat Working Memory • An elevated radial maze was used to test rat memory for the location of food. • Rats are very accurate at remembering which arms they have already visited, and not repeating. • Extra-maze (outside) cues are used to remember. • When cues were attached to a curtain and then rotated, the rats had to rotate their visits. • Rats learned to avoid the arms that never had food, using long term memory.

16. 8.21 An 8-arm radial maze

17. 8.22 Cues positioned at the end of each arm of a radial maze could be rotated or transported

18. Two Explanations • Retrospective code – the rat might remember where it has been before. • Prospective code – the rat might remember places it has not yet visited (looking forward). • Memory load is highest at the task’s beginning. • Both rats and pigeons use both kinds of codes. • Delays inserted into the task were most disruptive in the middle, not at beginning or end.

19. 8.23 Retrospective and prospective coding in working memory Asked to peck at 5 different lighted keys Exploring arms in an elevated maze

20. Reference (Long Term) Memory • It is difficult to determine which kind of long term memory is used in conditioning because animals cannot speak. • Procedural, declarative, semantic, episodic. • Episodic memory was demonstrated in jays using mealworms & peanuts. • They learned that over time, the mealworms might “spoil” and so searched for peanuts instead

21. 8.24 Training procedure and predictions

22. 8.25 Number of searches by scrub jays at peanut or mealworm sites Note the Interaction

23. Behavior is Sensitive to Time • Animals have an internal sense of time. • When activities occur at certain times, animals can use time of day cues as CSs or occasion setters to predict or locate food. • Circadian rhythms govern activity. • Zeitgeibers link rhythms to the environment. • Animals can also detect time intervals: • Inhibition of delay in classical conditioning. • Scallops in fixed interval (FI) operant schedules.

24. 8.26 Pigeons can use time of day cues to set the occasion for which of two keys will be reinforced

25. Interval Timing Experiments • Temporal generalization gradients can be produced by reinforcing animals for responding to a signal of a specific duration. • Peak procedure – a stimulus is presented, then the first response after some time interval is reinforced (the animal must wait until then). • Shorter intervals were judged more accurately.

26. 8.27 Results from the peak procedure

27. Scalar Property • The ability of animals to judge longer and shorter intervals equally well is an example of Weber’s law. • Perceived differences are a constant proportion of the value being judged. • The amount of error in longer intervals is proportionate to the length of the interval. • The animal may be comparing the lapsed time to the previously reinforced interval.

28. 8.28 Other examples of superposition in interval timing

29. Temporal Bisection • Skinner gave rats a task where they had to press the right lever after a short interval and the left lever after a long interval. • Rats pressed the right and left levers equally often when intervals in the middle were presented. • This result was the same when 2/4 sec and 4/8 sec intervals were used. • Regardless of intervals, the rats always behaved as if they were comparing ratios.

30. How do they do it? • Internal clock model – clock, memory and a comparator. • Information processing approach. • Multiple oscillator model – oscillators start with the task and are monitored in working memory. • Multiple-time-scale model – memory strength is associated with the reinforcer.

31. 8.29 An information-processing model of timing has clock, memory, and decision components

32. 8.30 How multiple oscillators can tell time

33. Cues Guiding Spatial Behavior • Dead reckoning – an internal sense of direction guides behavior. • Beacons – cues near the goal that guide behavior. • Landmarks – cues not near the goal but with a fixed relationship to it. • Humans use landmarks differently than pigeons.

34. 8.31 Performance of pigeons taught to find rewards (Part 1)

35. 8.31 Performance of humans taught to find rewards (Part 2)

36. Geometric Models • Chang found that rats use geometric information in addition to cues to find food. • Preference for the opposite corner (a mistake) suggested that cues alone were not being used. • When cues were removed, preference for the opposite corner (a mistake) increased. • One short wall and one long one exists for both the correct choice and the wrong one.

37. 8.32 Apparatus and results of experiments reported by Cheng Cues removed Mistaken preference for the opposite corner increases

38. Evidence for Mental Maps • Radial maze – rats orient toward arms then make microchoices about which to enter. • Memory guides “blind” choices obscured by doors. • Water maze – rats must swim to find a submerged platform. • Rats found the platform even with the start place changed – landmarks from the room were used.

39. 8.33 A rat in a water maze (Part 1)

40. 8.33 Paths taken by rats on test trials in the water-maze (Part 2) Old location was searched first