The Influence of Endogenous and Exogenous Spatial Attention on Decision Confidence

Spatial attention allows us to make more accurate decisions about events in our environment. Decision confidence is thought to be intimately linked to the decision making process as confidence ratings are tightly coupled to decision accuracy. While both spatial attention and decision confidence have been subjected to extensive research, surprisingly little is known about the interaction between these two processes. Since attention increases performance it might be expected that confidence would also increase. However, two studies investigating the effects of endogenous attention on decision confidence found contradictory results. Here we investigated the effects of two distinct forms of spatial attention on decision confidence; endogenous attention and exogenous attention. We used an orientation-matching task, comparing the two attention conditions (endogenous and exogenous) to a control condition without directed attention. Participants performed better under both attention conditions than in the control condition. Higher confidence ratings than the control condition were found under endogenous attention but not under exogenous attention. This finding suggests that while attention can increase confidence ratings, it must be voluntarily deployed for this increase to take place. We discuss possible implications of this relative overconfidence found only during endogenous attention with respect to the theoretical background of decision confidence.

Supplementary Information: S1 Analysis. Non-parametric (permutation-based) Analysis of Covariance (ANCOVA). To get an estimate of the effects of attention on confidence after controlling for performance differences we performed a non-parametric (permutation-based) ANCOVA. After adjusting for performance accuracy, attention continued to have a significant effect on confidence, with F = 18.75, p < 0.001. The performance adjusted means for confidence under endogenous, exogenous and neutral attention were 0.88, 0.84 and 0.84, respectively. Post-hoc comparison on the adjusted values revealed a significant difference between endogenous and no-cue condition (t (22) = -3.11, p = 0.015) and between endogenous and exogenous condition (t (22) = -4, p = 0.002). No significant difference could be detected between exogenous and no-cue condition (t (22) = 0.088, p = 1). This analysis was done using the Fathom toolbox 52 for Matlab.

Experiment instructions:
You are taking part in a psychophysical experiment. We are trying to learn something about how visual stimuli are perceived and processed.
Throughout the experiment we will track your eye movements. So first we need to calibrate the eye-tracker. To do this there will be little targets appearing at different positions on the screen. Please look at every target and keep looking there until it disappears and the next one appears.
To ensure a quality of the eye data, please keep your head as still as possible in the headrest.
Try to only remove it during the breaks you are offered (every quarter of the trials) If you accidentally move your head please tell the examiner because the Eye-Tracker will need to be recalibrated. Additionally please try to only blink between the trials as this might also influence the quality of the data.
Please always look at the small black dot as long as it is presented on the screen.
During the experiment you will see gratings with or without cues. There will be an explanation trial, where you don't have to fixate the fixation point and can look at the grating and the cues to get an impression how they look.
Your task will be to remember the orientation of a stimulus and then try to match the orientation of another equal stimulus to the orientation of the one you briefly saw before.
You'll use the arrow keys on the keyboard to turn the second grating until it looks how you remember the first one. Don't worry if in the beginning everything happens really fast and you have the feeling you are not seeing anything. That will get better with time.
At the end of every trial you will be asked to rate how confident you are in your performance in the orientation matching task. You shall do that using a scale, where green means high confidence and red means low confidence. The range between can be used to express different gradations.
Before the actual experiment starts there will be a training session that will get harder while you solve it and where you don't have to make confidence ratings.

Do you have any questions?
Thanks in advance and have fun.