Both mean correct response times and error rates were assessed. Trials on which participants failed to respond were eliminated from analyses. We supplement each key Null Hypothesis Significance Test NHST with Bayesian analyses in this and the following experiment, particularly relevant for non-significant effects.
In all cases, Bayesian tests were computed with a half normal distribution with a mean of zero and the effect in the control condition as the prior standard deviation with an online Bayes calculator from Dienes, BF 10 indicates evidence in favour of an effect and BF 01 indicates evidence in favour of a null. We report the Bayes factor for the direction that the data favours e. Training phase. Control groups test. The response time data are presented in the left panel of Figure 2.
First, we analyzed the two control groups to assure that robust contingency effects were observed during test for both words and shapes. The pattern was similar for the shapes-only group. Experiment 1 response time left and percentage error right contingency effects low — high contingency as a function of group and phase, with standard error bars.
Compound-cue group test. Next, we turn to the compound-cue group. For errors, the contingency effect was non-significant for words high: 6. Cross-group comparisons. Robust contingency effects were observed in both training and test albeit only for response times at test in the compound-cue condition for both the words and the shapes. Thus, complete overshadowing was decidedly not observed. However, we next examined to what extent partial overshadowing might have been observed by directly comparing the compound-cue group to the controls using a series of ANOVAs comparing the contingency effect high vs.
For the word test trials, we used the words-only group as controls; and for the shape test trials, we used the shapes-only group as controls. Thus, the error results, unlike response times, do not provide clear evidence that there was no overshadowing at all.
It is also worth noting that a half-normal test is biased against inferences in favour of the null i. Contingency awareness. Correlations with the response time training and test effects are presented in Table 2. As can be observed, there was some albeit weak and inconsistent evidence for larger effects with increased contingency awareness.
In the absence of an overall overshadowing effect, no further analyses of the awareness data were conducted. In Experiment 1, no clear evidence for overshadowing was observed. That is: a a contingency effect was observed during the test phase for both shapes and words when shapes and words were trained together in compounds, and b this test effect for compound study was not smaller than the contingency effects observed for words and shapes after training of only words and shapes, respectively.
Evidence for a true null i. In any case, it seems evident that a substantial overshadowing effect was not observed: test effects were quite robust for both elements of the compound stimulus. The present results might indicate that overshadowing is, more generally, absent or very weak with incidental learning.
Of course, it could equally well be the case that incidental learning overshadowing effects are observable, only not with the present choice of stimulus dimensions i. This study also demonstrates for the first time that it is possible to observe transfer of learning from compound word-shape stimuli to each of the elements of the compounds i.
In Experiment 2, we turn to blocking, using an approach similar to that of Experiment 1. In fact, the design of Experiment 2 was identical, except that instead of having three groups with two blocks of one stimulus type, there were three training groups: one that was presented only words during an initial element training block words-first , a second that was presented only shapes during element training shapes-first , and a third overshadowing control that was presented both shapes and words during training identical to the compound cue group in Experiment 1.
Both of the first two groups then proceeded to a compound training blocking phase, and all participants then completed a test block. The relative stimulus frequencies for the words-first element, shapes-first element, and compound training blocks were identical to those for the words-only, shapes-only, and compound training blocks of Experiment 1 see Table 1.
The test block was also identical. With this design, we can establish whether participants show a larger test effect for the initially trained dimension i.
Because both words and shapes are used for both the blocking and blocked dimensions across subject conditions, an interaction between test item type words vs.
Note, too, that this is a rather liberal test for blocking, as a larger effect for Stimulus A over Stimulus X could potentially also be due to simply more training for Stimulus A. Thus, a failure to observe a difference between Stimulus A and X at test would argue even more strongly that blocking was not present. However, we also included an overshadowing group as a control. We also included a manipulation of instructions. Participants were additionally instructed to intentionally learn these contingencies while performing the task.
If deliberate rather than just incidental learning does play some role in cue competition effects, then we might be able to observe stronger evidence for cue competition effects with these instructions. We anticipated in advance that this manipulation should be more effective in producing cue competition effects, as it is known that human participants often produce such effects when deliberating over the contingencies see D.
Shanks, , for a review. Thus, our design included the within factors of contingency high vs. We actually conducted four experiments from subsets of this design. In particular, we initially conducted Experiment 2a with only incidental learning and no overshadowing group. No blocking was found.
Experiment 2b was then conducted as a more powerful replication with the addition of an overshadowing control group only partially relevant in the absence of a blocking interaction. Again, no blocking was found. Experiment 2c was then conducted as a replication but with instructions to learn reviewer requested. This time, there was partial evidence for blocking, similar to what we found in the combined data set.
Finally, Experiment 2d was conducted as a replication also reviewer requested of the full design but now with random assignment of participants to the six different groups to verify that the observed effects did not depend on between-experiment comparisons. Predictably, no differences were observed between identical conditions across experiments note that all four studies were identical, save for which between-group conditions were conducted in a given experiment.
The studies were combined based on reviewer suggestions to condense presentation of the experiments and to improve statistical power. There were participants total: participants in Experiment 2a 51 words-first, 60 shapes-first; non-instructed , in Experiment 2b 86 overshadowing, 88 words-first, 76 shapes-first; non-instructed , in Experiment 2c 98 overshadowing, 99 words-first, 96 shapes-first; instructed , and in Experiment 2d and overshadowing, and 95 words-first, 86 and shapes-first, non-instructed and instructed, respectively.
As in the previous study, these sample sizes were determined a priori, Experiment 2a as a guess, Experiment 2b as a much larger replication, Experiment 2c to roughly match the instructed sample to the non-instructed sample, and Experiment 2d as a rough doubling of all six between-group conditions to ensure no differences were observed between a full-factorial experiment and the between-experiment differences we had already observed.
Participants were recruited from the same pool as Experiment 1 and none participated in more than one experiment.
Apparatus, design, procedure, and data analysis. The apparatus, design, procedure, and data analysis of Experiment 2 were identical in all respects to Experiment 1 with the following exceptions. First, there were six between-subject groups, made of the orthogonal combination of study condition words-first, shapes-first, and overshadowing and instruction condition instructed vs.
After the practice block identical to Experiment 1 , participants completed one block of trials, identical to the words-only, shapes-only, or compound cue blocks used in Experiment 1. A second compound training blocking phase consisting of trials followed this, and was the same as the compound-cue block in Experiment 1.
The stimulus dimension that appeared in both blocks had the same contingencies in both e. The test block was also the same as in Experiment 1. With the words-first and shapes-first groups, we are primarily interested in the magnitude of the test effect for words and shapes as a function of whether words or shapes were the initially trained or blocked dimension.
Thus, for the words-first group, words were the blocking dimension and shapes were the blocked dimension. The reverse was true for the shapes-first group. If blocking occurs, the contingency effect at test should be smaller for the blocked dimension.
The only difference in the procedure for instructed participants was an additional instruction page, which was added before the training phase:. Each distracting stimulus might cause a specific colour most often. For instance, one word or shape might cause the colour to be blue most often, another red most often, and another green most often.
Some stimuli might not be predictive at all. Try to learn which stimuli are predictive of which colours. At the end of the experiment, you will be tested to see whether you have correctly determined the pairings.
Experiment 2 additionally included an overshadowing group, which was identical to that in Experiment 1. The subjective awareness question was also slightly altered to the following changes in italics :.
This experiment was divided into four parts, starting with a practice phase coloured rectangles and ending with a test phase coloured words or coloured shapes. During the third part of the experiment, one word-shape combination was presented most often in blue, another word-shape combination was presented most often in red, and a third word-shape combination was presented most often in green. Naturally, subjective awareness for the overshadowing group could only be probed for the word-shape compounds i.
The objective awareness instruction was also slightly modified changes in italics and each word and each shape was tested separately to get objective awareness measures for both the blocking and blocked dimensions:. For the following questions, indicate in which colour you think that the following words and shapes were presented most often using the same keys as before.
Element and compound training phases. Test phase response times. The results for the test phase are presented in Figure 3. Experiment 2 response time top and percentage error bottom contingency effects low — high contingency as a function of group and stimulus type during the test phase, with standard error bars.
Despite the lack of an interaction, the blocking interaction was tested separately for the non-instructed and instructed participants. Thus, there was no evidence for blocking. However, there was an asymmetry in the blocking effect for instructed participants. Thus, while there were some global hints of a true effect for instructed participants in response times including a marginally significant 19 ms blocking interaction and suggestive evidence for a larger effect in instructed participants, the response times did not prove definitive, unlike the remaining dependent variables to be discussed.
Test phase error rates. Synonyms Attentional learning ; Selective learning. This is a preview of subscription content, log in to check access. In: Lubow RE. Behav Brain Sci —20 Google Scholar. Hemsley DR A simple or simplistic? Kapur S Psychosis as a state of aberrant salience: a framework linking biology, phenomenology, and pharmacology in schizophrenia. If you are training using luring, rest assured that dogs will pay more attention to a treat used as a lure than a verbal command if the lure is not faded quickly.
In this case, the most salient stimulus the lure overshadows the other stimulus the verbal command. Another example: If you are training your dog to sit and you say "sit" while you move your head downwards, guess what will likely happen? Your head movement will overshadow your verbal command. Dogs are masters in looking at our body language, so our movements are much more salient than our voices.
What will happen then? You may end up with a dog that will not sit if you just say "sit" and fail to move your head downwards, but will sit promptly sit if you do move your head, even without saying "sit. If you are not into dog training but into human psychology or you failed to grasp the lure example, here is another example: a man is admiring a beautiful woman walking by the street as he is driving the car.
Yet the red stop sign is more salient, so he pays attention to it and stops looking at the pretty woman to watch for passing cars. In this case, the red stop sign has overshadowed the pretty lady and thankfully so!
In blocking, a stimulus becomes irrelevant if it is presented together with an already familiar stimulus. For instance, if you are training your dog German commands and say "down" and "platz," the dog will likely not rely on "platz" because the familiar word "down" provides enough information, plus it has a history of reinforcement, so who cares about "platz.
If you are looking for a human example, here is one to make the concept clearer. If you have always stopped at a red stop sign, the day you find an intersection with both a red and a black stop sign, you will likely attend more to the red sign because it provides more information to you as it has a history of grabbing your attention.
In this case, the red stop signs are blocking the black ones from having an effect on you. Overshadowing is when two or more more stimuli are present, and one stimulus produces a stronger response than the other because it is more relevant or salient. Superconditioning is a term associated with classical conditioning. It occurs when a conditioned stimulus and an unconditioned stimulus are paired in the presence of a previously established conditioned inhibitor.
What is the difference between overshadowing and blocking? Overshadowing comes as a result of the differences between the stimuli in characteristics like intensity. Blocking is a result of prior experience with one part of a compound stimulus. We put on music to block out the sound of the traffic. Entry 1 of 2 1 : the act or an instance of wiping out : complete or utter destruction. Annihilation, in physics, reaction in which a particle and its antiparticle collide and disappear, releasing energy.
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