Experiment 2: Context generalization following delayed context shift

Hypothesis 1

It was hypothesized following an immediate delay subjects would be able to discriminate between two contextsSubjects trained in context A and immediately

tested in context B for would not run down the runway as quickly in B as they did in A; whereas subjects trained in context A and tested in context A would show little to no difference in their time to run down a run way

Hypothesis 2

It was hypothesized following an longer delay subjects would generalize the two contexts as indicated by similar performance between the two groups Subjects trained in context A and tested in context B a

week later would run down the runway as quickly in B as they initially did in A suggesting that the subjects generalized the two contexts; similarly subjects trained in context A and tested in context A would show little to no difference in their time to run down a run way

Subjects

16 female Long-Evans rats approximately 90-120 days oldSubjects were quasi-randomly assigned to

one of four groups (n=4 per group)

Apparatus & Materials

Both runways had the following dimesions 61” long X 5” wide and the walls 4” high and contained a food cup at the end; food cup contained one fruit loop

Context A Walls were gray Floor was a wire grid 44” off the floor Covered with a plexiglass lid Normal light conditions

Apparatus & Materials

Context BWalls were whiteFloor was covered with coarse grit sandpaper24.5” off floorNo lid on top Illuminated by three desk lampsContained lemon scent throughout

Figure 1a & 1b Context A

Figure 2a & 2b Context B

Procedure

The first 3 days of the study were used as pre-testing in order to get the subjects acclimated to context A Each day every subject was given 5 trials, a trial consisted of the

subject starting at one end and running to the other end and ended once the subject began eating the fruit loop

Each subject was given 5 minutes per trial, if the subject failed to perform they would be removed and the next trial would begin

Once the subjects reached asymptotic performance all subjects were given one day of testing in context A in order to establish baseline performance Each subject was given 3 trials

Procedure

Following baseline testing subjects were quasi-randomly assigned to one of four groups (n=4 per group) Each subject was given 3 trials

Two groups were either tested in context A or context B two days after baseline testing

The other two groups were tested in context A or context B one week after baseline testing

Procedure

Initial performance as well as baseline performance was analyzed to determine whether there were any group differences

The dependent measure was the difference in time it took to run down the alley from baseline to testing Averaged across 3 trials Positive score indicates improved performance; subject running

quicker Negative score indicates that it took longer to reach the end

Initial performance

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2 Days 1 Week 2 Days 1 Week 2 Days 1 Week

Pre-Training D1 Pre-Training D2 Pre-Training D3

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Initial performance

Source Sum of Squares df Mean Square F Sig.

PreTest 195418.5 2 97709.25 74.29302 0

PreTest * Context 593.1666667 2 296.583333 0.225507 0.799784

PreTest * Delay 657.1666667 2 328.583333 0.249838 0.780928

PreTest * Context *

Delay 1502 2 751 0.571021 0.572438

Error(PreTest) 31564.5 24 1315.1875

Context 1250.520833 1 1250.52083 0.214391 0.651632

Delay 2366.020833 1 2366.02083 0.405634 0.536155

Context * Delay 4162.6875 1 4162.6875 0.713657 0.414758

Error 69994.75 12 5832.89583

Initial performance

Pre-Training D1 Pre-Training D2 Pre-Training D3

Mean 2 Days 1 Week 2 Days 1 Week 2 Days 1 Week

Same 203.25 154 111.75 69.75 27.75 21

Different 169.5 178.5 68 73.25 18.75 18.25

PreD1 PreD2 PreD3

S.D. 2 Days 1 Week 2 Days 1 Week 2 Days 1 Week

Same 106.1928 71.37693 61.15213 42.08226071 16.02862024 11.6046

Different 69.52458 64.09108 34.28313 35.71530951 11.35414755 7.632169

Initial performance

A context X delay X day repeated measures ANOVA demonstrated a significant effect of day F(2,24)=74.29, p <.05) and no significant group or delay differences (p’s >.05)

This suggests that all subjects were performing similar prior to any experimental manipulation, but were demonstrating improved performance by the final day of pretesting as indicated by a reduced time to reach the end of the alley

Baseline

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Baseline

SourceSum of Squares df

Mean Square F Sig.

Context 18.0625 1 18.0625 0.251962 0.62478

Delay 22.5625 1 22.5625 0.314734 0.585113

Context * Delay 39.0625 1 39.0625 0.5449 0.474599

Error 860.25 12 71.6875

Baseline

Baseline Baseline

Mean 2 Days 1 Week

Same 11.75 17.25

Different 12.75 12

S.D. 2 Days 1 Week

Same 2.986079 15.54295

Different 4.856267 3.559026

Baseline

A context X delay ANOVA demonstrated no significant differences between any of the groups (p’s >.05)

This suggests that during baseline testing there were no significant difference between any of the subjects’ performance

Mean difference from baseline

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Mean difference from baseline

SourceSum of Squares df

Mean Square F Sig.

Context 64 1 64 8.347826 0.013595

Delay 64 1 64 8.347826 0.013595

Context * Delay 121 1 121 15.78261 0.00185

Error 92 12 7.66666667

Mean difference from baseline

Mean 2 days 1 Week

Same 0.5 -1

Different -9 0.5

S.D. 2 days 1 Week

Same 2.89 2.31

Different 3.92 1.29

Mean difference from baseline

A context X delay ANOVA found a significant main effect for context , F(1,12) = 8.35 and delay F(1,12) = 8.35, as well as a significant context X delay interaction F(1,12) = 15.78, p’s<.05

The significant effect of context indicates that subjects tested in a different context performed significantly poorer, as indicated by a slower running time during testing

The significant effect of delay suggests that subjects tested immediately following baseline testing were able to discriminate between the two contexts

The significant context X delay interaction suggests that subjects tested in a different context 2 days after baseline are able to discriminate between the two environments whereas subjects tested in the different context 1 week later is generalizing the different context as indicated by similar performance to subjects tested in the same environment as baseline at both 2 days and 1 week

Some extra information

There are numerous books and articles about this topic Generalization and discrimination of context Recall cues Contextual learning

Remember to discuss this in an overall context, don’t just simply regurgitate try to integrate

The challenge in this is to try to relate this to other aspects of the literature or even find conflicting studies In other words why are our findings important, what can people

take from this study

Some extra information

An important paper Gisquet-Verrier, P., & Alexinsky, T. (1986). Does

contextual change determine long-term forgetting? Animal Learning & Behavior, 14(4), 349-358.

Can use this, but it can’t count towards the two paper min. requirement (but it is very useful)

http://www.psychonomic.org/search/view.cgi?id=10855

Some extra information

Remember if you need help ask