diff --git a/code/useful_functions.py b/code/useful_functions.py
index 39ba01e..edea81b 100644
--- a/code/useful_functions.py
+++ b/code/useful_functions.py
@@ -275,7 +275,7 @@ def power_spectrum(stimulus):
     # computes firing rates
     rate = firing_rate(binary, dt = dt)
     # creates power spectrum
-    freq, power = welch(rate, fs = 1/dt, nperseg = 2**16, noverlap = 2**15)
+    freq, power = welch(binary, fs = 1/dt, nperseg = 2**16, noverlap = 2**15)
     return freq, power
 
 def prepare_harmonic(frequency, category, num_harmonics, color):