103_17_full

103_17_full - PSYC 103 Winter 2011 Lecture 17 Timing and Order Review session Tuesday Feb 22 8:00 PM Pepper canyon hall 109 Timing Why be sensitive

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Unformatted text preview: PSYC 103 Winter 2011 Lecture 17 Timing and Order Review session Tuesday Feb. 22 @ 8:00 PM Pepper canyon hall 109 Timing Why be sensitive to time? •  Control patterns of activity •  Measure rates of occurrence Periodic timing: the ability of animals to respond at a particular time •  Circadian rhythms •  Nocturnal, diurnal, crepuscular Interval timing: the ability of animals to respond on the basis of specific durations Peak procedure Weber’s law: the accuracy of the judgment is proportional to the magnitude of the stimulus Interval timing Temporal generalization •  Lever press for food after a fixed duration of darkness •  Responding to other durations produces a generalization gradient Rats can be trained to remember multiple intervals Interval timing How do animals compute intervals? need to estimate the actual and recall the remembered time Three possible relationships between the duration of remembered time relative to the passage of actual time Remembered time equals actual time Remembered time less than actual time Remembered time longer than actual time Subjective time 0 Real time 60 s Subjective time linear logarithmic Time left to reward Time-left procedure Training: •  Left lever: 60s •  Right lever: 30s Testing: •  present 30 s lever at different points in the 60 s interval Result: A given interval of real time is subjectively the same whether it occurs at the beginning or end of a longer interval Time is measured linearly Subjective time follows real-time Interval timing How do animals compute intervals •  Subtraction of remembered and actual durations? •  Computing the ratio of remembered & actual ? Bisecting the interval •  press left lever for long (12 s) tone •  press right lever for short (3s) tone •  test with intermediate duration tones for 50% r/l resp • If subtraction: midpoint=7.5 • If ratio: midpoint=6 Timing summary 1.  Subjective time grows linearly with real time 2.  Timing obeys Weber’s law: longer times are perceived and/or remembered with greater variance than shorter times •  Scalar property of timing 3.  Timing is multimodal light noise Species differences: •  rats, pigeons, humans tested most extensively •  sharpness of the peaks vary, but most data suggest that all these species time interval similarly Serial order Weisman et al. (1980): Serial recognition in pigeons: Red → Green → Food Green → Red → No food Red → Red → No food Green → Green → No food All solved with little trouble Baleine et al. (1995): Response chaining in rats Lever press → Chain pull → Food Serial recognition: representation of first element enters into association with second, stored in LTM Response chaining: S-R associations – conditioning chamber associated with lever, which is associated with chain pull . . . 10 Serial order Simultaneous chaining Animals presented with array of several stimuli. Must make same response to each in correct sequence to gain reward Pigeons Terrace (1987, 1991): Birds had to peck stimuli A-B-C-D-E (which were presented simultaneously) in this order for food reward D A C E B 11 Serial order Pigeons - Hard to learn, - need to be introduced to the problem slowly: -  first A-B then A-B-C, then A-B-C-D, finally A-B-C-D-E - Solution of the problem = sequence of discriminations (response chaining): Onset of array = Cue to peck A Withdrawal from A = Cue to Peck B Withdrawal from B = Cue to peck C Etc. - Supported by poor performance in test trials in which just B and C illuminated (no cue to peck B) 12 Pigeon data D’Amato & Colombo (1988) •  Respond equally fast to the first and second items of all subsets •  Respond at chance to subsequences of internal items (e.g. BC) Rule base responding: •  If A is present respond first to it, then anything else •  If E is present respond first to anything then to E Serial order: Chunking Terrace (1991) - Simultaneous chaining much easier if sequence is: A-B-C-X-Y A, B, C = colours X, Y = shapes - Series is chunked into two separate lists. - Pigeons working memory limited 3 items…..? The mean number of sessions of training required in the various stages of a simultaneous chaining experiment with pigeons. Stimuli A, B, and C were colors, and stimuli X and Y were geometric shapes Serial order Monkeys D’Amato & Colombo (1988) Monkeys had to touch stimuli on a screen in correct order to acquire food: - Easy problem for monkeys -  Also, monkeys will press B then C when presented with this pair (unlike pigeons) -  Monkeys demonstrate: -  Magnitude effect: faster to respond to first stimulus in a pair, when it is near the start of list -  Distance effect: as number of intervening items is increased between items in a test pair, so time taken to make first response decreases 15 Serial order Monkeys -  Magnitude effect: faster to respond to first stimulus in a pair, when it is near the start of list -  Distance effect: as number of intervening items is increased between items in a test pair, so time taken to make first response decreases Left-hand panel: The mean time taken to select the first item of a test pair of stimuli by monkeys, after they had been trained with the simultaneous chain A–B–C–D–E. Right-hand panel: The mean time to select the second item of the test pairs by the same monkeys as function of the number of items that separate the members of the pair in the training list (adapted from D’Amato & Colombo, 1988). Serial order Terrace et al. (1997) -  Animals construct a spatial representation of 4 slots, in serial order -  Different spatial representations can be integrated… 17 (iv) Transitive inference IF: A > B And IF: B >C Then: A >C Transitive inference Gillan (1981) - Chimpanzees presented with pairs of containers, in one of which was hidden food: A+ BB+ CC+ DD+ E -  Chimps eventually performed appropriately. Then tested with B vs D -  One chimp, Sadie, selected B in preference to D consistently on 12 test trials but other 2 chimps did not -  Sadie capable of transitive inference? How is this knowledge represented? -  B is better than C, C is better than D….? – McGonigle & Chalmers (1992) – squirrel monkeys -  If this is the case then it should be easier to choose A from AB than B from BD Not so, in fact the opposite was observed: symbolic distance effect 18 (iv) Transitive inference Symbolic distance effect D’Amato (1991): Transitive inference training results in the acquisition of a chain: A-B-C-D-E But, pigeons are capable of transitive inference (e.g. Staddon, 1991), and they are poor at simultaneous chaining Von Fersen et al. (1991): Value transfer - Transitive inference training results in: - A = highly valued (always paired with food) - B, C, D = moderately valued (intermittently paired with food) - E = no value ( never paired with food) - Training also results in associations forming within pairs (e.g. between A and B, between C and D) - B preferred to D at test because of value transferred from A to B and from E to D Zentall & Sherburne (1994): Simultaneous discrimination with pigeons A and B presented together (pecking A consistently rewarded) C and D presented together (pecking C intermittently reinforced) At test: Birds preferred B to D which supports value transfer analysis 19 ...
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This note was uploaded on 03/24/2012 for the course PSYC 103 taught by Professor Pearlberg during the Spring '07 term at UCSD.

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